Support Codex 0.134 approvals

Use available approval decisions from the app-server schema, preserve structured policy decisions in callbacks, and keep approval rendering aligned with normal tool-call output.

Also simplify thread commands, clear stale active turns more carefully, and update command/help docs.

PLAN.md

@@ -52,7 +52,7 @@ Before implementation, carefully read the official docs and check against the gu
 - Telegram UX:
   - One-to-one chats only; reject groups, supergroups, and channels.
   - Allowlisted Telegram user IDs only.
-  - Commands: `/start`, `/help`, `/new`, `/threads`, `/resume`, `/fork`, `/archive`, `/status`, `/cancel`, `/workspaces`, `/workspace`, `/model`, `/sandbox`, `/diff`.
+  - Commands: `/start`, `/help`, `/new`, `/thread`, `/fork`, `/archive`, `/status`, `/cancel`, `/workspaces`, `/workspace`, `/model`, `/sandbox`, `/diff`.
   - Plain text continues the active Codex thread, creating one if needed.
   - Send assistant messages and rendered tool/status blocks as separate Telegram messages; chunk only when a single message exceeds Telegram limits.
   - Send long output, logs, and diffs as chunked messages.
@@ -77,7 +77,7 @@ Any interactive related test that requires user action should be done properly -
 - Integration tests:
   - Use a low/mini model in codex for testing.
   - Verify initialize, thread start, turn start, streamed output, approval, and cancellation.
-  - Verify `/start`, `/new`, `/threads`, `/resume`, `/workspace`, `/cancel`, image input, and document staging.
+  - Verify `/start`, `/new`, `/thread`, `/workspace`, `/cancel`, image input, and document staging.
   - Verify non-allowlisted users are rejected and logged.
 
 - Manual acceptance: