Add SessionEnd hooks for thread teardown (#33895)

## What changed

- Add the `SessionEnd` hook event to hook configuration, protocol schemas, analytics, and the hooks browser.
- Run matching hooks for root threads during shutdown, including app-server archive, delete, idle unload, and graceful shutdown. Flush the transcript first and provide the session ID, transcript path, working directory, and `reason: "other"`.
- Keep teardown bounded: hook output is advisory, the default timeout is one second, configured timeouts are capped at three seconds, and async hooks run synchronously with a warning.

## Testing

- Cover transcript availability, matcher selection, timeout normalization, ignored control output, subagent exclusion, archive/delete ordering, and graceful shutdown of multiple loaded threads.

GitOrigin-RevId: 5d19a658677a137caf836ed5042dcb43f5eb6d1a

codex-rs/analytics/src/events.rs

@@ -1254,6 +1254,7 @@ fn analytics_hook_event_name(event_name: HookEventName) -> &'static str {
         HookEventName::PreCompact => "PreCompact",
         HookEventName::PostCompact => "PostCompact",
         HookEventName::SessionStart => "SessionStart",
+        HookEventName::SessionEnd => "SessionEnd",
         HookEventName::UserPromptSubmit => "UserPromptSubmit",
         HookEventName::SubagentStart => "SubagentStart",
         HookEventName::SubagentStop => "SubagentStop",