fix: restore remote OpenCode providers and startup errors

- Fix OpenChamber proxying to the correct OpenCode host for remote VPS setups
- Show a clear empty-state error when OpenCode is not reachable
- Harden session event routing for early or mismatched directory events

packages/web/server/lib/opencode/lifecycle.js

@@ -204,7 +204,7 @@ export const createOpenCodeLifecycleRuntime = (deps) => {
     }
 
     try {
-      const response = await fetch(`http://127.0.0.1:${state.openCodePort}/session`, {
+      const response = await fetch(buildOpenCodeUrl('/session', ''), {
         method: 'GET',
         headers: getOpenCodeAuthHeaders(),
         signal: AbortSignal.timeout(2000),