feat(dashboard): comprehensive config UI with help and descriptions

- Add InfoButton component with click-to-toggle popover for field help
- Add SectionDescription component for section intro paragraphs
- Add AlertRuleToggle component with grouped threshold controls
- Add detailed info and helper text for every field in all sections
- Convert Commands section to toggleable command list with descriptions
- Add dropdowns for severity_min, fire state, connection type, LLM backend
- Add region management: Add/Delete buttons with confirmation
- Group alert rules by category: Infrastructure, Power, Utilization, Health
- Remove hardcoded placeholders and Idaho-specific text
- Fix config.py DashboardConfig dataclass decorator
- Fix main.py MessageRouter initialization

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

meshai/main.py

@@ -420,7 +420,7 @@ class MeshAI:
             health_engine=self.health_engine,
             mesh_reporter=self.mesh_reporter,
             env_store=self.env_store,
-            notification_router=self.notification_router,
+            # notification_router not used by MessageRouter
         )
 
         # Responder