feat: add Nav Panel with URL-routed section navigation

- Add NavPanel widget for room-level section navigation
- Add Control Room feature router with URL routes:
  - /control-room/containers
  - /control-room/networks
  - /control-room/volumes
  - /control-room/images
- Sections: Containers, Networks, Volumes, Images
- Navigation updates URL and vice versa (deep-linkable)
- Remove redundant Stacks section (handled by filter panel)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

lib/features/control_room/presentation/pages/control_room_page.dart

@@ -1,37 +1,80 @@
 import 'package:flutter/material.dart' hide Stack;
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:go_router/go_router.dart';
 import 'package:tatlock_ui/features/control_room/containers/presentation/pages/containers_list_page.dart';
+import 'package:tatlock_ui/features/control_room/router.dart';
 import 'package:tatlock_ui/features/control_room/stacks/data/repositories/stack_repository_impl.dart';
 import 'package:tatlock_ui/features/control_room/stacks/domain/entities/stack.dart';
 import 'package:tatlock_ui/features/control_room/stacks/presentation/pages/stack_detail_page.dart';
 import 'package:tatlock_ui/features/control_room/stacks/presentation/providers/stacks_provider.dart';
 import 'package:tatlock_ui/features/control_room/stacks/presentation/widgets/stack_list_tile.dart';
 import 'package:tatlock_ui/shared/layouts/widgets/filter_panel.dart';
+import 'package:tatlock_ui/shared/layouts/widgets/nav_panel.dart';
 
-/// Main Control Room page with stacks sidebar and containers view.
+/// Control Room navigation sections.
+enum ControlRoomSection {
+  containers('containers', 'Containers', Icons.dns),
+  networks('networks', 'Networks', Icons.hub),
+  volumes('volumes', 'Volumes', Icons.storage),
+  images('images', 'Images', Icons.photo_library);
+
+  const ControlRoomSection(this.id, this.label, this.icon);
+
+  final String id;
+  final String label;
+  final IconData icon;
+
+  NavSection toNavSection() => NavSection(
+        id: id,
+        label: label,
+        icon: icon,
+      );
+}
+
+/// Main Control Room page with nav panel and section content.
 class ControlRoomPage extends ConsumerWidget {
-  const ControlRoomPage({super.key});
+  const ControlRoomPage({
+    super.key,
+    this.section = ControlRoomSection.containers,
+  });
+
+  /// The current section to display.
+  final ControlRoomSection section;
 
   @override
   Widget build(BuildContext context, WidgetRef ref) {
-    final selectedStack = ref.watch(selectedStackProvider);
+    final colorScheme = Theme.of(context).colorScheme;
 
     return Scaffold(
       body: Row(
         children: [
-          // Stacks sidebar
-          const _StacksSidebar(),
+          // Nav Panel - section navigation
+          NavPanel(
+            title: 'Sections',
+            icon: Icons.dns_outlined,
+            sections: ControlRoomSection.values
+                .map((s) => s.toNavSection())
+                .toList(),
+            selectedId: section.id,
+            onSectionSelected: (id) {
+              final newSection = ControlRoomSection.values.firstWhere(
+                (s) => s.id == id,
+              );
+              // Navigate to section URL
+              context.go(pathForSection(newSection));
+              // Clear stack selection when changing sections
+              ref.read(selectedStackProvider.notifier).clear();
+            },
+          ),
           // Divider
           VerticalDivider(
             width: 1,
             thickness: 1,
-            color: Theme.of(context).colorScheme.outlineVariant,
+            color: colorScheme.outlineVariant,
           ),
-          // Main content area - shows either all containers or stack detail
+          // Section content
           Expanded(
-            child: selectedStack == null
-                ? const ContainersListPage()
-                : StackDetailPage(stackId: selectedStack),
+            child: _SectionContent(section: section),
           ),
         ],
       ),
@@ -39,9 +82,98 @@ class ControlRoomPage extends ConsumerWidget {
   }
 }
 
-/// Sidebar showing stacks list (Filter Panel per UI_LAYOUT.md).
-class _StacksSidebar extends ConsumerWidget {
-  const _StacksSidebar();
+/// Renders content for the selected section.
+class _SectionContent extends ConsumerWidget {
+  const _SectionContent({required this.section});
+
+  final ControlRoomSection section;
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    switch (section) {
+      case ControlRoomSection.containers:
+        return const _ContainersSection();
+      case ControlRoomSection.networks:
+      case ControlRoomSection.volumes:
+      case ControlRoomSection.images:
+        return _PlaceholderSection(section: section);
+    }
+  }
+}
+
+/// Containers section with optional stack filter.
+class _ContainersSection extends ConsumerWidget {
+  const _ContainersSection();
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final selectedStack = ref.watch(selectedStackProvider);
+    final colorScheme = Theme.of(context).colorScheme;
+
+    return Row(
+      children: [
+        // Stacks filter panel
+        const _StacksFilterPanel(),
+        // Divider
+        VerticalDivider(
+          width: 1,
+          thickness: 1,
+          color: colorScheme.outlineVariant,
+        ),
+        // Main content - containers list or stack detail
+        Expanded(
+          child: selectedStack == null
+              ? const ContainersListPage()
+              : StackDetailPage(stackId: selectedStack),
+        ),
+      ],
+    );
+  }
+}
+
+/// Placeholder for sections not yet implemented.
+class _PlaceholderSection extends StatelessWidget {
+  const _PlaceholderSection({required this.section});
+
+  final ControlRoomSection section;
+
+  @override
+  Widget build(BuildContext context) {
+    final colorScheme = Theme.of(context).colorScheme;
+    final textTheme = Theme.of(context).textTheme;
+
+    return Center(
+      child: Column(
+        mainAxisSize: MainAxisSize.min,
+        children: [
+          Icon(
+            section.icon,
+            size: 64,
+            color: colorScheme.outline,
+          ),
+          const SizedBox(height: 16),
+          Text(
+            section.label,
+            style: textTheme.headlineSmall?.copyWith(
+              color: colorScheme.onSurfaceVariant,
+            ),
+          ),
+          const SizedBox(height: 8),
+          Text(
+            'Coming soon',
+            style: textTheme.bodyMedium?.copyWith(
+              color: colorScheme.outline,
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+}
+
+/// Stacks filter panel for Containers section (includes "All Containers" option).
+class _StacksFilterPanel extends ConsumerWidget {
+  const _StacksFilterPanel();
 
   @override
   Widget build(BuildContext context, WidgetRef ref) {