feat: Enhance dashboard with filtering options and sync SLM status

- Added a new filtering system to the dashboard for device types and statuses.
- Implemented asynchronous SLM status synchronization to update the Emitter table.
- Updated the status snapshot endpoint to sync SLM status before generating the snapshot.
- Refactored the dashboard HTML to include filter controls and JavaScript for managing filter state.
- Improved the unit detail page to handle modem associations and cascade updates to paired devices.
- Removed redundant code related to syncing start time for measuring devices.

backend/routers/roster.py

@@ -2,20 +2,32 @@ from fastapi import APIRouter, Depends
 from sqlalchemy.orm import Session
 from datetime import datetime, timedelta
 from typing import Dict, Any
+import asyncio
+import logging
 import random
 
 from backend.database import get_db
 from backend.services.snapshot import emit_status_snapshot
+from backend.services.slm_status_sync import sync_slm_status_to_emitters
 
 router = APIRouter(prefix="/api", tags=["roster"])
+logger = logging.getLogger(__name__)
 
 
 @router.get("/status-snapshot")
-def get_status_snapshot(db: Session = Depends(get_db)):
+async def get_status_snapshot(db: Session = Depends(get_db)):
     """
     Calls emit_status_snapshot() to get current fleet status.
-    This will be replaced with real Series3 emitter logic later.
+    Syncs SLM status from SLMM before generating snapshot.
     """
+    # Sync SLM status from SLMM (with timeout to prevent blocking)
+    try:
+        await asyncio.wait_for(sync_slm_status_to_emitters(), timeout=2.0)
+    except asyncio.TimeoutError:
+        logger.warning("SLM status sync timed out, using cached data")
+    except Exception as e:
+        logger.warning(f"SLM status sync failed: {e}")
+
     return emit_status_snapshot()