fix(studio): chain config dir + spawn path + doc URLs

Track the platform rename: the hub spawn path is now ~/.chain/bin/chain
(was ~/.fai/bin/fai.exe on Windows — both dir and binary were stale, so
Studio could not launch the hub after the config-dir rename), the
~/.fai/* help strings become ~/.chain/*, FAI_REGISTRY_TOKEN ->
CHAIN_REGISTRY_TOKEN, and the two in-app doc URLs point at the public
fai/chain repo (fai/platform was renamed to the private fai/chain-private).
The .fai module bundle extension is left unchanged (format phase).
flutter analyze: no issues.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/l10n/app_localizations.dart

@@ -323,7 +323,7 @@ abstract class AppLocalizations {
   /// No description provided for @errServiceUnavailableForStepHint.
   ///
   /// In en, this message translates to:
-  /// **'The module requires a service (e.g. ollama, playwright) the operator hasn\'t declared. Add it under `services:` in ~/.fai/config.yaml.'**
+  /// **'The module requires a service (e.g. ollama, playwright) the operator hasn\'t declared. Add it under `services:` in ~/.chain/config.yaml.'**
   String get errServiceUnavailableForStepHint;
 
   /// No description provided for @errMissingValue.
@@ -875,7 +875,7 @@ abstract class AppLocalizations {
   /// No description provided for @channelsBlurb.
   ///
   /// In en, this message translates to:
-  /// **'Switch hub channel (writes ~/.fai/current-channel and restarts the daemon). Connect just changes Studio\'s wire.'**
+  /// **'Switch hub channel (writes ~/.chain/current-channel and restarts the daemon). Connect just changes Studio\'s wire.'**
   String get channelsBlurb;
 
   /// No description provided for @channelsActionsTooltip.
@@ -1649,7 +1649,7 @@ abstract class AppLocalizations {
   /// No description provided for @storeDocsErrorAuth.
   ///
   /// In en, this message translates to:
-  /// **'The registry requires authentication to fetch this README. Set FAI_REGISTRY_TOKEN in the daemon\'s environment and restart the hub.'**
+  /// **'The registry requires authentication to fetch this README. Set CHAIN_REGISTRY_TOKEN in the daemon\'s environment and restart the hub.'**
   String get storeDocsErrorAuth;
 
   /// No description provided for @storeDocsErrorNetwork.
@@ -1991,7 +1991,7 @@ abstract class AppLocalizations {
   /// No description provided for @modulesNoneHint.
   ///
   /// In en, this message translates to:
-  /// **'Run `chain install <capability-name>` or check ~/.fai/modules/.'**
+  /// **'Run `chain install <capability-name>` or check ~/.chain/modules/.'**
   String get modulesNoneHint;
 
   /// No description provided for @modulesReloadTooltip.
@@ -2279,7 +2279,7 @@ abstract class AppLocalizations {
   /// No description provided for @registryCredentialsBlurb.
   ///
   /// In en, this message translates to:
-  /// **'Token used to download .fai modules from a registry behind a signin wall (Forgejo, GitHub-private). Stored at ~/.fai/registry-token, mode 0600. The FAI_REGISTRY_TOKEN env var still wins when set.'**
+  /// **'Token used to download .fai modules from a registry behind a signin wall (Forgejo, GitHub-private). Stored at ~/.chain/registry-token, mode 0600. The CHAIN_REGISTRY_TOKEN env var still wins when set.'**
   String get registryCredentialsBlurb;
 
   /// No description provided for @registryTokenStatusConfigured.
@@ -2321,7 +2321,7 @@ abstract class AppLocalizations {
   /// No description provided for @registryTokenStorageHint.
   ///
   /// In en, this message translates to:
-  /// **'Saved locally to ~/.fai/registry-token. Never sent to a remote service.'**
+  /// **'Saved locally to ~/.chain/registry-token. Never sent to a remote service.'**
   String get registryTokenStorageHint;
 
   /// No description provided for @registryTokenSavedToast.
@@ -2351,7 +2351,7 @@ abstract class AppLocalizations {
   /// No description provided for @hubAuthTokenBlurb.
   ///
   /// In en, this message translates to:
-  /// **'Bearer token used to authenticate Studio against a hub that has auth.tokens: configured (RBAC Level 2). Stored at ~/.fai/hub-auth-token, mode 0600. Studio sends it as Authorization: Bearer on every gRPC call.'**
+  /// **'Bearer token used to authenticate Studio against a hub that has auth.tokens: configured (RBAC Level 2). Stored at ~/.chain/hub-auth-token, mode 0600. Studio sends it as Authorization: Bearer on every gRPC call.'**
   String get hubAuthTokenBlurb;
 
   /// No description provided for @hubAuthTokenStatusConfigured.
@@ -2393,7 +2393,7 @@ abstract class AppLocalizations {
   /// No description provided for @hubAuthTokenStorageHint.
   ///
   /// In en, this message translates to:
-  /// **'Saved locally to ~/.fai/hub-auth-token. Studio reconnects after save so the new token takes effect immediately.'**
+  /// **'Saved locally to ~/.chain/hub-auth-token. Studio reconnects after save so the new token takes effect immediately.'**
   String get hubAuthTokenStorageHint;
 
   /// No description provided for @hubAuthTokenSavedToast.
@@ -2501,7 +2501,7 @@ abstract class AppLocalizations {
   /// No description provided for @maintenanceResetBlurb.
   ///
   /// In en, this message translates to:
-  /// **'Wipe operator state and start over with a clean hub. Stops every running daemon, atomically backs ~/.fai/ up, then recreates it with the binary, channel state, MCP / n8n / system-AI config, and registry token preserved. Restore by moving the backup directory back.'**
+  /// **'Wipe operator state and start over with a clean hub. Stops every running daemon, atomically backs ~/.chain/ up, then recreates it with the binary, channel state, MCP / n8n / system-AI config, and registry token preserved. Restore by moving the backup directory back.'**
   String get maintenanceResetBlurb;
 
   /// No description provided for @maintenanceKeepModulesTitle.
@@ -2513,7 +2513,7 @@ abstract class AppLocalizations {
   /// No description provided for @maintenanceKeepModulesSubtitle.
   ///
   /// In en, this message translates to:
-  /// **'Default behaviour wipes ~/.fai/modules/ so a fresh install can verify the module-fetch path end-to-end.'**
+  /// **'Default behaviour wipes ~/.chain/modules/ so a fresh install can verify the module-fetch path end-to-end.'**
   String get maintenanceKeepModulesSubtitle;
 
   /// No description provided for @maintenanceKeepDataTitle.
@@ -2525,7 +2525,7 @@ abstract class AppLocalizations {
   /// No description provided for @maintenanceKeepDataSubtitle.
   ///
   /// In en, this message translates to:
-  /// **'Default behaviour wipes ~/.fai/data/ so the audit chain restarts from a fresh genesis and the bundled sample flows re-import on first daemon start.'**
+  /// **'Default behaviour wipes ~/.chain/data/ so the audit chain restarts from a fresh genesis and the bundled sample flows re-import on first daemon start.'**
   String get maintenanceKeepDataSubtitle;
 
   /// No description provided for @maintenanceResetButton.
@@ -2549,7 +2549,7 @@ abstract class AppLocalizations {
   /// No description provided for @maintenanceResetConfirmBody.
   ///
   /// In en, this message translates to:
-  /// **'This stops every daemon, moves ~/.fai/ to a timestamped backup, and starts fresh. The backup is fully restorable. Continue?'**
+  /// **'This stops every daemon, moves ~/.chain/ to a timestamped backup, and starts fresh. The backup is fully restorable. Continue?'**
   String get maintenanceResetConfirmBody;
 
   /// No description provided for @maintenanceResetConfirmButton.
@@ -2795,7 +2795,7 @@ abstract class AppLocalizations {
   /// No description provided for @errPermissionDeniedHint.
   ///
   /// In en, this message translates to:
-  /// **'The hub\'s operator policy blocks this action. Check `~/.fai/config.yaml`.'**
+  /// **'The hub\'s operator policy blocks this action. Check `~/.chain/config.yaml`.'**
   String get errPermissionDeniedHint;
 
   /// No description provided for @errFailedPrecondition.
@@ -2819,7 +2819,7 @@ abstract class AppLocalizations {
   /// No description provided for @errInternalHint.
   ///
   /// In en, this message translates to:
-  /// **'Check the hub logs at `~/.fai/logs/`. If this repeats, please report it.'**
+  /// **'Check the hub logs at `~/.chain/logs/`. If this repeats, please report it.'**
   String get errInternalHint;
 
   /// No description provided for @errUnavailable.
@@ -2843,7 +2843,7 @@ abstract class AppLocalizations {
   /// No description provided for @errUnauthenticatedHint.
   ///
   /// In en, this message translates to:
-  /// **'Set `FAI_REGISTRY_TOKEN` or sign in through Settings before retrying.'**
+  /// **'Set `CHAIN_REGISTRY_TOKEN` or sign in through Settings before retrying.'**
   String get errUnauthenticatedHint;
 
   /// No description provided for @errCopyDetail.
@@ -3155,7 +3155,7 @@ abstract class AppLocalizations {
   /// No description provided for @doctorServicesEmptyHint.
   ///
   /// In en, this message translates to:
-  /// **'add to ~/.fai/config.yaml under services:'**
+  /// **'add to ~/.chain/config.yaml under services:'**
   String get doctorServicesEmptyHint;
 
   /// No description provided for @doctorPillLoaded.
@@ -4139,7 +4139,7 @@ abstract class AppLocalizations {
   /// No description provided for @settingsSecurityPanelBody.
   ///
   /// In en, this message translates to:
-  /// **'Tokens the hub holds on the operator\'s behalf. Stored in ~/.fai/ with mode 0600; never sent in telemetry.'**
+  /// **'Tokens the hub holds on the operator\'s behalf. Stored in ~/.chain/ with mode 0600; never sent in telemetry.'**
   String get settingsSecurityPanelBody;
 
   /// No description provided for @settingsMaintenancePanelTitle.