feat: NUT (Network UPS Tools) service provider + provider-agnostic UI

Add full NUT support as a polling-based service provider:
- Async TCP client for upsd protocol (port 3493, configurable)
- 8 event types: online, on_battery, low_battery, battery_restored,
  comms_lost, comms_restored, replace_battery, overload
- 3 bot commands: /status, /devices, /battery
- 38 Jinja2 templates (EN+RU notification + command templates)
- Database: tracking config fields, migration, seeds
- Frontend: provider form with host/port/credentials, grid items, i18n

Provider-agnostic UI improvements:
- Remove hardcoded 'immich' defaults from all config forms
- Dynamic collection labels per provider type (Albums/Repos/Boards/UPS Devices)
- Capability-driven test types instead of provider type checks
- Template variable helpers for all providers (was Immich-only)
- Guard Immich-only shared link check to Immich providers
- Auto-clear stale global provider filter from localStorage
- EntitySelect search placeholder shows current selection
- Fix noneLabel in linked target config selectors

New CLAUDE.md rule #8: no provider-specific hardcoding

packages/server/src/notify_bridge_server/services/dispatch_helpers.py

@@ -83,6 +83,15 @@ def event_allowed_by_config(event: ServiceEvent, tc: TrackingConfig) -> bool:
         "task_completed": tc.track_task_completed,
         # Scheduler events
         "scheduled_message": tc.track_scheduled_message,
+        # NUT (UPS) events
+        "ups_online": tc.track_ups_online,
+        "ups_on_battery": tc.track_ups_on_battery,
+        "ups_low_battery": tc.track_ups_low_battery,
+        "ups_battery_restored": tc.track_ups_battery_restored,
+        "ups_comms_lost": tc.track_ups_comms_lost,
+        "ups_comms_restored": tc.track_ups_comms_restored,
+        "ups_replace_battery": tc.track_ups_replace_battery,
+        "ups_overload": tc.track_ups_overload,
     }
     return flag_map.get(event_type, True)