fix(vscode): skip unsupported OpenChamber event stream

Shared session-list subscriptions opened server-only event and URL-token routes against the webview origin, causing repeated 403 responses. Skip the control-stream subscription in VS Code while preserving OpenCode bridge sync and polling.

Validated with regression tests, UI type-check and lint, and the VS Code webview build. The reported gray-screen crash remains unconfirmed pending user logs.

packages/vscode/src/DOCUMENTATION.md

@@ -103,6 +103,13 @@ The webview build emits each worker as one self-contained file. VS Code webviews
 
 Message and part ordering is owned by [`packages/ui/src/sync/DOCUMENTATION.md`](../../ui/src/sync/DOCUMENTATION.md#session-message-loading). The VS Code webview consumes that shared sync implementation; bridge and proxy runtimes pass OpenCode records through without adding runtime-specific ordering.
 
+The OpenChamber control stream (`/api/openchamber/events`) requires the
+OpenChamber server, which the extension does not run. `subscribeOpenchamberEvents`
+therefore returns a no-op subscription in VS Code before resolving URLs or
+opening a connection. Session sync still uses the OpenCode SSE bridge and
+global session polling. Sending the control stream to the webview origin caused
+repeated `403` responses and URL-token requests to `/auth/url-token`.
+
 ## Extension guideline
 
 When adding new bridge route families: