feat(studio): module uninstall + Doctor daemon control (v0.17.0)

UI parity for Windows operators who never touch a shell:

- Module sheet gains an Uninstall button at the bottom.
  Two-step confirmation, then calls UninstallModule + closes
  the sheet + refreshes the Modules page.

- Doctor page picks up two new sections:
  * Daemon files — log / config / audit DB / modules /
    flows / pid, each with a one-click "Open" button that
    shells out to the OS handler (open / xdg-open /
    explorer).
  * Daemon control — Restart / Stop / Status buttons that
    spawn `fai daemon …`. Captured stdout/stderr renders
    inline so the operator sees what happened.

- Update banner gains an "Apply update" button that spawns
  `fai update apply --channel <c>`. The previous version
  showed the command as text — Windows users had no way to
  execute it.

- Event log panel gains a "Verify now" button that re-runs
  the chain check (via the existing doctor refresh).

New SystemActions helper resolves the `fai` binary via
$FAI_BIN → PATH → `~/.fai/bin/fai` (or the Windows
equivalent), so the buttons work whether the operator
restarted their shell after installing or not.

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

lib/widgets/fai_module_sheet.dart

@@ -15,9 +15,11 @@ class FaiModuleSheet extends StatefulWidget {
 
   const FaiModuleSheet({super.key, required this.moduleName});
 
-  /// Convenience launcher used from the Modules list.
-  static Future<void> show(BuildContext context, String name) {
-    return showModalBottomSheet<void>(
+  /// Convenience launcher used from the Modules list. Resolves
+  /// to `true` when the operator uninstalled the module — the
+  /// caller (Modules page) refreshes its list on that signal.
+  static Future<bool> show(BuildContext context, String name) async {
+    final r = await showModalBottomSheet<bool>(
       context: context,
       backgroundColor: Theme.of(context).colorScheme.surfaceContainer,
       isScrollControlled: true,
@@ -28,6 +30,7 @@ class FaiModuleSheet extends StatefulWidget {
       ),
       builder: (_) => FaiModuleSheet(moduleName: name),
     );
+    return r ?? false;
   }
 
   @override
@@ -36,6 +39,7 @@ class FaiModuleSheet extends StatefulWidget {
 
 class _FaiModuleSheetState extends State<FaiModuleSheet> {
   late final Future<ModuleDetail> _future;
+  bool _uninstalling = false;
 
   @override
   void initState() {
@@ -43,6 +47,50 @@ class _FaiModuleSheetState extends State<FaiModuleSheet> {
     _future = HubService.instance.moduleInfo(widget.moduleName);
   }
 
+  Future<void> _confirmAndUninstall(ModuleDetail detail) async {
+    final ok = await showDialog<bool>(
+      context: context,
+      builder: (ctx) => AlertDialog(
+        title: const Text('Uninstall module?'),
+        content: Text(
+          'Removes ${detail.name} v${detail.version} from this hub. '
+          'Flows that reference it will fail at the next run. '
+          'A `module.uninstalled` audit event is recorded.',
+        ),
+        actions: [
+          TextButton(
+            onPressed: () => Navigator.pop(ctx, false),
+            child: const Text('Cancel'),
+          ),
+          FilledButton(
+            onPressed: () => Navigator.pop(ctx, true),
+            style: FilledButton.styleFrom(
+              backgroundColor: Theme.of(ctx).colorScheme.error,
+              foregroundColor: Theme.of(ctx).colorScheme.onError,
+            ),
+            child: const Text('Uninstall'),
+          ),
+        ],
+      ),
+    );
+    if (ok != true || !mounted) return;
+    setState(() => _uninstalling = true);
+    try {
+      final r = await HubService.instance.uninstallModule(detail.name);
+      if (!mounted) return;
+      ScaffoldMessenger.of(context).showSnackBar(
+        SnackBar(content: Text('Uninstalled ${r.name} v${r.version}.')),
+      );
+      Navigator.pop(context, true);
+    } catch (e) {
+      if (!mounted) return;
+      setState(() => _uninstalling = false);
+      ScaffoldMessenger.of(context).showSnackBar(
+        SnackBar(content: Text('Uninstall failed: $e')),
+      );
+    }
+  }
+
   @override
   Widget build(BuildContext context) {
     final theme = Theme.of(context);
@@ -73,7 +121,13 @@ class _FaiModuleSheetState extends State<FaiModuleSheet> {
                   ),
                 )
               else
-                Flexible(child: _Body(detail: snapshot.data!)),
+                Flexible(
+                  child: _Body(
+                    detail: snapshot.data!,
+                    uninstalling: _uninstalling,
+                    onUninstall: () => _confirmAndUninstall(snapshot.data!),
+                  ),
+                ),
             ],
           );
         },
@@ -102,8 +156,14 @@ class _Handle extends StatelessWidget {
 
 class _Body extends StatelessWidget {
   final ModuleDetail detail;
+  final bool uninstalling;
+  final VoidCallback onUninstall;
 
-  const _Body({required this.detail});
+  const _Body({
+    required this.detail,
+    required this.uninstalling,
+    required this.onUninstall,
+  });
 
   @override
   Widget build(BuildContext context) {
@@ -196,6 +256,29 @@ class _Body extends StatelessWidget {
                 )
                 .toList(),
           ),
+        const SizedBox(height: FaiSpace.xxl),
+        Row(
+          children: [
+            const Spacer(),
+            OutlinedButton.icon(
+              onPressed: uninstalling ? null : onUninstall,
+              icon: uninstalling
+                  ? const SizedBox(
+                      width: 14,
+                      height: 14,
+                      child: CircularProgressIndicator(strokeWidth: 2),
+                    )
+                  : const Icon(Icons.delete_outline, size: 16),
+              label: Text(uninstalling ? 'Uninstalling…' : 'Uninstall'),
+              style: OutlinedButton.styleFrom(
+                foregroundColor: theme.colorScheme.error,
+                side: BorderSide(
+                  color: theme.colorScheme.error.withValues(alpha: 0.5),
+                ),
+              ),
+            ),
+          ],
+        ),
       ],
     );
   }