feat: locale-aware command templates, debounced auto-sync, entity pickers

- Locale-aware templates: CommandTemplateSlot now has a locale column,
  allowing each slot to have per-language variants (EN/RU). Templates
  are resolved at runtime from the Telegram user's language_code.

- Merged system configs: "Default Commands (EN)" and "(RU)" merged
  into a single "Default Commands" config with locale-aware slots.
  Migration handles existing data automatically.

- Configurable command descriptions: hardcoded COMMAND_DESCRIPTIONS
  replaced with desc_* template slots (desc_status, desc_help, etc.)
  that users can customize per locale. setMyCommands registers all
  locales explicitly.

- Removed locale from CommandConfig: no longer needed since locale
  is derived from the Telegram user's language at runtime.

- Debounced command auto-sync: after command config/tracker changes,
  affected bots are marked dirty and synced after a 30s debounce
  window. Manual "Sync with Telegram" button still works.

- Entity pickers in LinkedTargetsSection: replaced 6 plain <select>
  elements with EntitySelect components (search, icons, keyboard nav).
  Added onselect callback and size="sm" props to EntitySelect.

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

@@ -30,6 +30,10 @@ async def start_scheduler() -> None:
     from .telegram_poller import start_command_listener_polling
     await start_command_listener_polling()
 
+    # Start debounced command auto-sync scheduler
+    from .command_sync import start_sync_scheduler
+    start_sync_scheduler()
+
 
 async def _load_tracker_jobs() -> None:
     """Load enabled trackers and schedule polling jobs."""