feat(v2): add permission mode passthrough and fix agent stop-on-close

- Add permission_mode field to AgentQueryOptions (Rust, sidecar, bridge)
  flowing from controller through sidecar to SDK; defaults to
  bypassPermissions, supports default mode
- Fix AgentPane onDestroy bug: remove stopAgent() from onDestroy (fires
  on layout remounts), move stop-on-close to TilingGrid onClose handler
- Bundle SDK into sidecar via esbuild (remove --external flag)

v2/src/lib/adapters/agent-bridge.ts

@@ -11,6 +11,7 @@ export interface AgentQueryOptions {
   max_turns?: number;
   max_budget_usd?: number;
   resume_session_id?: string;
+  permission_mode?: string;
   remote_machine_id?: string;
 }