feat: standardize device type for Sound Level Meters (SLM)

- Updated all instances of device_type from "sound_level_meter" to "slm" across the codebase.
- Enhanced documentation to reflect the new device type standardization.
- Added migration script to convert legacy device types in the database.
- Updated relevant API endpoints, models, and frontend templates to use the new device type.
- Ensured backward compatibility by deprecating the old device type without data loss.

backend/main.py

@@ -111,26 +111,6 @@ async def startup_event():
     await start_scheduler()
     logger.info("Scheduler service started")
 
-    # Sync all SLMs to SLMM on startup
-    logger.info("Syncing SLM devices to SLMM...")
-    try:
-        from backend.services.slmm_sync import sync_all_slms_to_slmm, cleanup_orphaned_slmm_devices
-        from backend.database import SessionLocal
-
-        db = SessionLocal()
-        try:
-            # Sync all SLMs from roster to SLMM
-            sync_results = await sync_all_slms_to_slmm(db)
-            logger.info(f"SLM sync complete: {sync_results}")
-
-            # Clean up orphaned devices in SLMM
-            cleanup_results = await cleanup_orphaned_slmm_devices(db)
-            logger.info(f"SLMM cleanup complete: {cleanup_results}")
-        finally:
-            db.close()
-    except Exception as e:
-        logger.error(f"Error syncing SLMs to SLMM on startup: {e}")
-
 @app.on_event("shutdown")
 def shutdown_event():
     """Clean up services on app shutdown"""