feat(studio): channel switcher, autostart toggle, Store redesign (v0.18.0)

UI parity for operators who never touch a CLI, plus a Store
that reads more like an app store.

Settings dialog:
- Channel rows gain a popup menu: Connect / Make active /
  Enable autostart / Disable autostart. "Connect" still
  re-points Studio's wire; "Make active" actually writes
  ~/.fai/current-channel via `fai channel switch`.
- Inline output panel surfaces the spawned binary's stdout
  on success or stderr on failure, so operators see what
  happened without opening a terminal.

Store page rewrite:
- Big top search bar with a clear button. Live filter on
  every keystroke.
- Horizontal category strip auto-populated from the index;
  segmented status row (All / Published / Alpha / Planned),
  Installed-only chip, result count.
- Grid of cards that reflows to fit the viewport — replaces
  the previous single-column list. Each card shows
  category-aware icon, version, status, tagline preview, and
  a one-click Install (or Details for installed / planned).
- Per-module detail sheet renders the full bilingual
  description with a DE/EN toggle, separate Required-
  capabilities + Required-host-services sections, repo link,
  Read-docs button. Install + Uninstall live at the bottom.
- StoreItem and HubService.searchStore now carry the German
  tagline + description so the locale toggle has something
  to switch to.

SystemActions extended with `faiChannelSwitch`,
`faiDaemonEnable`, `faiDaemonDisable` so Settings can spawn
the right CLI without each call site reimplementing the
`fai` resolution rules.

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

lib/data/system_actions.dart

@@ -55,6 +55,32 @@ class SystemActions {
     return _runFai(['update', 'apply', '--channel', channel]);
   }
 
+  /// Switch the active channel pointer at `~/.fai/current-channel`.
+  /// The CLI also restarts the daemon for the new channel, so the
+  /// caller does not need a follow-up restart.
+  static Future<({bool ok, String stdout, String stderr})> faiChannelSwitch(
+    String channel,
+  ) async {
+    return _runFai(['channel', 'switch', channel]);
+  }
+
+  /// Install the platform-native autostart unit for [channel]
+  /// (launchd plist on macOS, systemd-user unit on Linux). On
+  /// Windows the platform CLI returns a "not supported" exit
+  /// status that the caller surfaces as an error message.
+  static Future<({bool ok, String stdout, String stderr})> faiDaemonEnable(
+    String channel,
+  ) async {
+    return _runFai(['daemon', 'enable', '--channel', channel]);
+  }
+
+  /// Remove the autostart unit installed by [faiDaemonEnable].
+  static Future<({bool ok, String stdout, String stderr})> faiDaemonDisable(
+    String channel,
+  ) async {
+    return _runFai(['daemon', 'disable', '--channel', channel]);
+  }
+
   static Future<({bool ok, String stdout, String stderr})> _runFai(
     List<String> args,
   ) async {