## Why

The SCUM companion client, robot workflows, and run-side helpers contain useful server-operations behavior, but their current shape mixes SCUM product semantics with ad hoc transport, credentials, host paths, and executor responsibilities. We need a first-party bridge that lets `game.scum` own SCUM-specific commands, snapshots, and pages while Platform and Run provide only generic secure infrastructure.

## What Changes

- Add a generic Game Client Bridge capability for durable, authenticated component commands, command lifecycle tracking, cancellation, expiry, idempotency, fencing, result recording, and versioned snapshot ingest/query.
- Add SCUM plugin operations on top of that bridge: command catalog, snapshot schemas, page contracts, permissions, and approval levels for players, squads, vehicles, flags, sessions, logs, database query templates, backups, restarts, and events.
- Adapt the real `scum_client` model into a plugin-owned companion component that registers through the Platform Client Manager path, heartbeats securely, claims bridge commands, returns results, and uploads typed snapshots.
- Keep independent Run free of SCUM business logic. Run may deploy, supervise, execute bounded process/file/SQLite/archive capabilities, and report lifecycle state, but SCUM semantics remain declared by the plugin and mediated by Platform.
- Replace unsafe legacy patterns from the reference projects with platform-mediated equivalents: no arbitrary terminal, no arbitrary SQL, no raw host paths, no shared credentials, no direct run sockets, no insecure TLS skip, and no script-based arbitrary URL self-update.

## Capabilities

### New Capabilities

- `game-client-bridge`: Defines the platform bridge for authenticated companion clients, durable command queues, command result flow, cancellation/expiry semantics, snapshot ingestion, snapshot querying, retention, and audit trails.
- `scum-operations`: Defines the SCUM plugin-owned operational model, including typed commands, typed snapshots, pages, permissions, approval policy, log semantics, database query templates, backup/restart policies, and client integration requirements.

### Modified Capabilities

- None.

## Impact

- Backend Platform: new API routes, DTOs, domain types, repositories, services, persistence models, validation rules, permissions, and audit events for the Game Client Bridge.
- Platform Web: bridge-aware SCUM operation views that preserve the magical-girl crystal-moonlight console direction and do not receive raw credentials or host paths.
- Plugins: `plugins/examples/scum-server-plugin` gains real `game.scum` command catalogs, snapshot schemas, page contracts, permissions, and lifecycle/client declarations aligned with the real companion client.
- Companion Client: `scum_client` behavior is migrated from legacy shared-token endpoints to Platform Client Manager registration/session and bridge command/snapshot APIs.
- Run Executor: no SCUM-specific source is added to this repository; Run remains an independent generic executor for declared process, file, SQLite, artifact, and packaging operations.