fix(approvals,l10n,theme): usertest findings — localized prompts, no-data confirm, .chain log path, honest wording, AA contrast

- approvals: empty/legacy hub prompts render the localized fallback;
  approving without show: data asks for conscious confirmation first
- chain_log: write to ~/.chain/logs/studio-errors.log (was .fai),
  one-time best-effort migration of the legacy file + rotation sibling
- l10n: 'manipulationssicher' -> 'manipulationserkennend', neutral
  WORM-1 blurb, doctor pill 'Integritätskette v1', federation hint
  says the CA authenticates the first connect (DE+EN)
- theme: muted text token now >=4.5:1 on canvas, cards and elevated
  dark surfaces (was 3.7:1 on cards)

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

lib/pages/approvals.dart

@@ -10,6 +10,24 @@ import '../theme/tokens.dart';
 import '../widgets/widgets.dart';
 import 'welcome.dart' show showFaiDoc;
 
+/// The fixed English sentence pre-0.21 hubs baked into stored
+/// approvals when the flow gave no `prompt:`. Newer hubs store the
+/// empty prompt verbatim.
+const _legacyHubPromptDefault =
+    'Please review and approve this step before continuing.';
+
+/// Reviewer-facing prompt with fallbacks: an empty prompt (the flow
+/// gave none) renders the localized default, and the legacy English
+/// default from old hub rows is mapped onto the same localized
+/// default so it stops showing English inside a German UI.
+String displayApprovalPrompt(AppLocalizations l, String prompt) {
+  final trimmed = prompt.trim();
+  if (trimmed.isEmpty || trimmed == _legacyHubPromptDefault) {
+    return l.approvalsRequestFallback;
+  }
+  return prompt;
+}
+
 class ApprovalsPage extends StatefulWidget {
   const ApprovalsPage({super.key});
 
@@ -68,6 +86,29 @@ class _ApprovalsPageState extends State<ApprovalsPage>
 
   Future<void> _approve(ApprovalRecord a) async {
     final l = AppLocalizations.of(context)!;
+    // No `show:` data attached → never approve on a reflex. Calmly
+    // explain and ask for a conscious confirmation first.
+    if (a.payloadPreview == null) {
+      final confirmed = await showDialog<bool>(
+        context: context,
+        builder: (ctx) => AlertDialog(
+          title: Text(l.approvalsNoDataConfirmTitle),
+          content: Text(l.approvalsNoDataConfirmBody),
+          actions: [
+            TextButton(
+              onPressed: () => Navigator.pop(ctx, false),
+              child: Text(l.buttonCancel),
+            ),
+            FilledButton(
+              onPressed: () => Navigator.pop(ctx, true),
+              child: Text(l.approvalsNoDataConfirmAction),
+            ),
+          ],
+        ),
+      );
+      if (confirmed != true) return;
+    }
+    if (!mounted) return;
     try {
       await HubService.instance.approve(a.id, _reviewer);
       _toast(l.approvalsApprovedToast(a.flowName, a.stepId));
@@ -77,6 +118,7 @@ class _ApprovalsPageState extends State<ApprovalsPage>
     }
   }
 
+
   Future<void> _reject(ApprovalRecord a) async {
     final l = AppLocalizations.of(context)!;
     final reason = await _promptReason(context);
@@ -558,9 +600,7 @@ class _ApprovalCard extends StatelessWidget {
           // step left the prompt empty, so the card is never reduced to
           // a cryptic flow id.
           Text(
-            approval.prompt.trim().isEmpty
-                ? l.approvalsRequestFallback
-                : approval.prompt,
+            displayApprovalPrompt(l, approval.prompt),
             style: theme.textTheme.titleMedium?.copyWith(
               fontWeight: FontWeight.w600,
             ),
@@ -850,7 +890,13 @@ class _HistoryDialog extends StatelessWidget {
                 ),
               ),
               const SizedBox(height: 4),
-              SelectableText(record.prompt, style: theme.textTheme.bodyMedium),
+              SelectableText(
+                displayApprovalPrompt(
+                  AppLocalizations.of(context)!,
+                  record.prompt,
+                ),
+                style: theme.textTheme.bodyMedium,
+              ),
               if (record.payloadPreview != null) ...[
                 const SizedBox(height: ChainSpace.md),
                 Text(