feat: live gRPC pages — drop mock data, talk to the real hub

Studio's three MVP pages now pull live data from a running hub
via fai_dart_sdk. Mock fixture removed.

- data/hub.dart: HubService singleton wraps fai_dart_sdk's
  HubClient and exposes UI-friendly types (ModuleSummary,
  AuditEvent, PendingApproval) so pages don't import protobuf.
- pages/modules.dart: FutureBuilder against listModules,
  groups CapabilityEntry rows by module, retry-on-error UI.
- pages/audit.dart: 2s polling Timer, status bar shows
  "live (polling 2s)" or "disconnected — <error>".
- pages/approvals.dart: live listApprovals, Approve sends
  DecideApproval(APPROVE), Reject opens a reason dialog and
  sends DecideApproval(REJECT). Both refresh after success.
- Connection-error states across all pages: cloud_off icon +
  hint to start `fai serve` + Retry button.

When no hub is running the pages render their disconnected
state instead of crashing. When a hub is running, the data is
real — no more mock fixture.

Bumps fai_studio 0.1.0 -> 0.2.0.

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

lib/pages/approvals.dart

@@ -1,6 +1,6 @@
 import 'package:flutter/material.dart';
 
-import '../data/mock.dart';
+import '../data/hub.dart';
 
 class ApprovalsPage extends StatefulWidget {
   const ApprovalsPage({super.key});
@@ -10,20 +10,121 @@ class ApprovalsPage extends StatefulWidget {
 }
 
 class _ApprovalsPageState extends State<ApprovalsPage> {
-  final _decided = <String>{};
+  late Future<List<PendingApproval>> _future;
+  // Hard-coded reviewer for the MVP; Phase 1+ wires this to an
+  // authenticated session.
+  final String _reviewer = 'studio-mvp';
+
+  @override
+  void initState() {
+    super.initState();
+    _future = HubService.instance.pendingApprovals();
+  }
+
+  void _refresh() => setState(() {
+        _future = HubService.instance.pendingApprovals();
+      });
+
+  Future<void> _approve(PendingApproval a) async {
+    try {
+      await HubService.instance.approve(a.id, _reviewer);
+      _refresh();
+    } catch (e) {
+      _showError('approve failed: $e');
+    }
+  }
+
+  Future<void> _reject(PendingApproval a) async {
+    final reason = await _promptReason(context);
+    if (reason == null || reason.isEmpty) return;
+    try {
+      await HubService.instance.reject(a.id, _reviewer, reason);
+      _refresh();
+    } catch (e) {
+      _showError('reject failed: $e');
+    }
+  }
+
+  void _showError(String msg) {
+    if (!mounted) return;
+    ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text(msg)));
+  }
+
+  Future<String?> _promptReason(BuildContext context) async {
+    final controller = TextEditingController();
+    return showDialog<String>(
+      context: context,
+      builder: (ctx) => AlertDialog(
+        title: const Text('Reject approval'),
+        content: TextField(
+          controller: controller,
+          autofocus: true,
+          decoration: const InputDecoration(
+            labelText: 'Reason (recorded in audit log)',
+          ),
+        ),
+        actions: [
+          TextButton(
+            onPressed: () => Navigator.pop(ctx, null),
+            child: const Text('Cancel'),
+          ),
+          FilledButton(
+            onPressed: () => Navigator.pop(ctx, controller.text),
+            child: const Text('Reject'),
+          ),
+        ],
+      ),
+    );
+  }
 
   @override
   Widget build(BuildContext context) {
     final theme = Theme.of(context);
-    final pending =
-        mockApprovals.where((a) => !_decided.contains(a.id)).toList();
     return Scaffold(
       appBar: AppBar(
         title: const Text('Pending Approvals'),
         centerTitle: false,
+        actions: [
+          IconButton(
+            icon: const Icon(Icons.refresh),
+            tooltip: 'Reload',
+            onPressed: _refresh,
+          ),
+        ],
       ),
-      body: pending.isEmpty
-          ? Center(
+      body: FutureBuilder<List<PendingApproval>>(
+        future: _future,
+        builder: (context, snapshot) {
+          if (snapshot.connectionState == ConnectionState.waiting) {
+            return const Center(child: CircularProgressIndicator());
+          }
+          if (snapshot.hasError) {
+            return Center(
+              child: Padding(
+                padding: const EdgeInsets.all(32),
+                child: Column(
+                  mainAxisAlignment: MainAxisAlignment.center,
+                  children: [
+                    Icon(
+                      Icons.cloud_off_outlined,
+                      size: 48,
+                      color: theme.colorScheme.error,
+                    ),
+                    const SizedBox(height: 16),
+                    Text('Hub unreachable: ${snapshot.error}'),
+                    const SizedBox(height: 16),
+                    FilledButton.tonal(
+                      onPressed: _refresh,
+                      child: const Text('Retry'),
+                    ),
+                  ],
+                ),
+              ),
+            );
+          }
+          final pending = snapshot.data ?? [];
+          if (pending.isEmpty) {
+            return Center(
               child: Padding(
                 padding: const EdgeInsets.all(32),
                 child: Column(
@@ -32,7 +133,8 @@ class _ApprovalsPageState extends State<ApprovalsPage> {
                     Icon(
                       Icons.check_circle_outline,
                       size: 64,
-                      color: theme.colorScheme.primary.withValues(alpha: 0.5),
+                      color: theme.colorScheme.primary
+                          .withValues(alpha: 0.5),
                     ),
                     const SizedBox(height: 16),
                     Text(
@@ -44,22 +146,23 @@ class _ApprovalsPageState extends State<ApprovalsPage> {
                   ],
                 ),
               ),
-            )
-          : ListView.separated(
-              padding: const EdgeInsets.all(24),
-              itemCount: pending.length,
-              separatorBuilder: (_, _) => const SizedBox(height: 16),
-              itemBuilder: (context, i) {
-                final a = pending[i];
-                return _ApprovalCard(
-                  approval: a,
-                  onApprove: () =>
-                      setState(() => _decided.add(a.id)),
-                  onReject: () =>
-                      setState(() => _decided.add(a.id)),
-                );
-              },
-            ),
+            );
+          }
+          return ListView.separated(
+            padding: const EdgeInsets.all(24),
+            itemCount: pending.length,
+            separatorBuilder: (_, _) => const SizedBox(height: 16),
+            itemBuilder: (context, i) {
+              final a = pending[i];
+              return _ApprovalCard(
+                approval: a,
+                onApprove: () => _approve(a),
+                onReject: () => _reject(a),
+              );
+            },
+          );
+        },
+      ),
     );
   }
 }