[Feature]: Gateway — bridge DeviceRegistry ↔ NodeRegistry by device_id

[theonlyhennygod]

Summary

Bridge the two existing registries so the gateway can answer one query: "Is the Mac with device_id X online and does it have capability Y?" Currently DeviceRegistry (SQLite, persistent identity) and NodeRegistry (in-memory, WS capability dispatch) don't talk to each other.

Problem

• DeviceRegistry persists pairing identity but has no concept of online/offline beyond last_seen (which only updates on HTTP requests).
• NodeRegistry has live WS-based capability dispatch but is ephemeral — no persistence, and uses a separate node_id from the device_id.
• The agent on the gateway has no single source of truth: "send this command to the Mac" requires consulting both, and there's no guarantee they refer to the same paired entity.

Proposal

• When a /ws/nodes WebSocket authenticates with a device's bearer token, treat the device_id == node_id.
• Schema migration on the devices table:
  • online_since TEXT (RFC3339) — non-null when the device has an active WS connection
  • node_id TEXT — populated from the device's UUID on first WS connection
  • capabilities sync from the WS register message (overrides the HTTP-pushed list from this branch's v1)
• On /ws/nodes register: look up device by token_hash, set online_since = now(), store advertised capabilities.
• On WS disconnect: clear online_since, keep the row.
• New gateway helper device_registry::is_online(device_id) -> bool and device_registry::find_online_with_capability(cap) -> Option<DeviceInfo> for the agent dispatcher to use.

Files

• crates/zeroclaw-gateway/src/api_pairing.rs — schema migration, new fields, helpers
• crates/zeroclaw-gateway/src/nodes.rs — bridge logic in the WS handler
• crates/zeroclaw-gateway/src/lib.rs — AppState wiring

Acceptance

• Existing devices migrate cleanly (additive ALTER TABLE).
• Mac connects to /ws/nodes with bearer token → its device row gets online_since populated and capabilities synced.
• Mac kills the connection → online_since clears within ~5s; row persists.
• Two device_registry regression tests prove migration + bridge logic.

Related

• Depends on the v1 capability sync from feat/desktop-onboarding.
• Sibling issue: persistent NodeClient on the desktop side (separate ticket).
• Capability handlers live in their own ticket (separate).

[theonlyhennygod]

Closing: v0.7.7 milestone is cancelled. The Tauri desktop app has been removed (PR #7026). Voice and clipboard items are deferred to a future milestone.