fix(web): enforce permissions for spawned sessions

[fengjikui]

Summary

• enforce existing OpenCode bash/external-directory permission checks before REST session creation
• enforce the same checks before WebSocket spawn creates a PTY session
• add focused handler tests proving denied web spawn requests do not call manager.spawn

Validation

• bun test test/web-permissions.test.ts test/websocket.test.ts test/pty-tools.test.ts
• bun run typecheck
• bun run format
• git diff --check
• bun run build:plugin
• bun run lint exits 0; it reports existing unrelated noNonNullAssertion warnings in test/notification-manager.test.ts

Notes

This keeps the web UI/API spawn path aligned with the existing pty_spawn permission behavior instead of allowing a separate path to create PTY sessions without consulting permission.bash.

[fengjikui]

Pushed 5e85c2e to address the failing unit job. The spawn-repeat test was machine-speed dependent and could open too many PTYs in one second; it now uses fixed repeat count with bounded concurrency while keeping env overrides for deeper stress runs.

Validation:

• bun test test/spawn-repeat.test.ts
• bun test test/web-permissions.test.ts
• bun format
• bun typecheck
• bun lint
• env -u HTTP_PROXY -u HTTPS_PROXY -u ALL_PROXY -u http_proxy -u https_proxy -u all_proxy bun unittest -> 64 pass, 1 skip, 0 fail

The latest GitHub Actions run is currently action_required with no jobs, so it looks like it needs maintainer approval to run on the fork update.

[fengjikui]

CI follow-up: the remaining red check is Devenv CI, but it fails before project code runs, during nix profile add nixpkgs#devenv with Nix bootstrap store path unpack-bootstrap-tools.sh reported as invalid. The PR-related jobs are green (test:e2e, format, lint, test, typecheck, and dependency-review).

I tried to rerun the failed job, but GitHub requires upstream repository admin rights for this run. I do not see a code change needed in this PR based on the current log.

[shekohex]

thank you!