feat(platform): add cloud_web platform for self-hosted IM gateways (#1282)

* feat(platform): add cloud_web platform for self-hosted IM gateways

Introduce the cloud_web platform with CWIP protocol support over websocket, long_poll, and gateway transports. Includes capability negotiation, inbound/outbound message handling, Web UI configuration with transport-specific fields and URL validation, documentation, build wiring, and integration tests.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(cloud-web): satisfy errcheck lint for Close/Stop returns

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(cloud-web): address PR review feedback for #1282

Resolve reviewer feedback and rebase onto latest main:

- CHANGELOG: add cloud_web entry under Unreleased / Added
- gateway: fail closed when token is unset (reject all inbound webhooks)
- New(): require public_url when register_url is set for gateway transport,
  mirror the rule in client-side validation, and add a regression test
- forward perm:* card actions via IsPermissionResponse so the engine drops
  stale permission clicks instead of leaking allow/deny into the agent prompt
- ko.json: add Korean translations for the cloud_web setup/fields keys
- split cloudweb_test.go by transport (ws/poll/gateway + shared test helper)

Co-authored-by: Cursor <cursoragent@cursor.com>

---------

Co-authored-by: jiagou123 <jiagou123@users.noreply.github.com>
Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: Your Name <you@example.com>

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### Added
 - **Reasonix agent**: new agent adapter for Reasonix multi-model coding agent, bridging via HTTP serve API (POST /submit, SSE /events, POST /approve). Supports default/yolo/plan permission modes, SSE auto-reconnect with backoff, and thinking accumulator. (#1281)
+- **cloud_web platform**: 新增 self-hosted IM Gateway 作为 first-class platform 接入 (CWIP v1 协议,支持 websocket / long_poll / gateway 3 种 transport,完整 inbound/outbound + capability negotiation + graceful degradation)。 详见 docs/cloud-web.md + #1282。
 
 ## Unreleased