fix(monitoring): repair silent-false-positive update badge + auto-update scheduling

Customer container status checks looked up containers by an exact expected
name. When a docker compose recreate got interrupted (e.g. a hung command
previously killed the whole update-all batch on timeout), Compose could leave
the old container renamed with a random hash prefix instead of removed. The
exact-name lookup then found nothing, returned None, and that silently
counted as "up to date" (green "Aktuell") instead of surfacing as unknown —
affecting 5 customers on the appliance whose containers were actually still
running under orphaned names.

- _run_cmd no longer raises on subprocess timeout, so one stuck customer
  can't abort the rest of a batch update
- repair_container_naming() self-heals orphaned hash-renamed containers by
  renaming them back before every status check and before recreate
- update-all loop now catches per-customer exceptions instead of aborting
- status responses expose "unknown" separately from "needs_update" so the UI
  shows a distinct grey badge instead of a false-positive green one
- new settings: automatic daily update check (on/off + time), with an
  independent toggle for whether it also auto-recreates customer containers

app/database.py

@@ -122,6 +122,11 @@ def _run_migrations() -> None:
         ("system_config", "git_repo_url", "TEXT"),
         ("system_config", "git_branch", "TEXT DEFAULT 'main'"),
         ("system_config", "git_token_encrypted", "TEXT"),
+        # Automatic NetBird image update check/apply
+        ("system_config", "auto_update_check_enabled", "BOOLEAN DEFAULT 0"),
+        ("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"),
     ]
     for table, column, col_type in migrations:
         if not _has_column(table, column):