feat(netbird): central control of client Automatic Updates across all customers

Lets the MSP admin control NetBird's own "Settings > Clients > Automatic
Updates" feature (client/peer auto-update, v0.61.0+) for every customer from
one place, instead of logging into each customer's dashboard individually.

- New deployments automatically capture a Personal Access Token during the
  existing /api/setup bootstrap call (create_pat=true), requiring
  NB_SETUP_PAT_ENABLED=true on the management container (now set by default
  in the compose template). Token is encrypted at rest per customer.
- Existing customers (deployed before this existed) can have a token pasted
  in manually from their own dashboard — verified before being stored.
- Settings > Docker Images: master default (version + force-update toggle)
  plus "Apply to All Customers" which pushes it to everyone with a token.
- Customer detail page: shows the customer's live current setting (read
  from their NetBird API, not cached) with per-customer override or
  "sync from default".
- New app/services/netbird_client_update_service.py wraps the customer's
  NetBird Management API (GET/PUT /api/accounts) for this.

app/database.py

@@ -127,6 +127,10 @@ def _run_migrations() -> None:
         ("system_config", "auto_update_check_time", "TEXT DEFAULT '03:00'"),
         ("system_config", "auto_update_apply_enabled", "BOOLEAN DEFAULT 0"),
         ("system_config", "auto_update_last_run_at", "TEXT"),
+        # NetBird client (peer) automatic-updates master default + per-customer PAT
+        ("deployments", "netbird_api_token_encrypted", "TEXT"),
+        ("system_config", "netbird_client_auto_update_version", "TEXT DEFAULT 'disabled'"),
+        ("system_config", "netbird_client_auto_update_always", "BOOLEAN DEFAULT 0"),
     ]
     for table, column, col_type in migrations:
         if not _has_column(table, column):