Add request_user_input auto-resolution window contract (#27256)

## Why

`request_user_input` is moving beyond its original plan-mode-only
workflow, and future default/goal-mode usage needs a way for the model
to ask helpful but non-blocking questions without forcing the turn to
wait forever. This PR adds an explicit `autoResolutionMs` contract so a
later client/runtime change can auto-resolve unanswered prompts after a
bounded window while leaving truly blocking questions unchanged.

This is contract plumbing only; it does not implement the client-side
timer or auto-selection behavior, and the model-facing description
treats the field as reserved unless the current runtime explicitly
supports auto-resolution.

## What Changed

- Added optional `autoResolutionMs` to the model-facing
`request_user_input` args and core `RequestUserInputEvent`.
- Added model-facing schema text for `autoResolutionMs` while marking it
reserved for runtimes that explicitly support auto-resolution.
- Bounds `autoResolutionMs` to `60_000..=240_000` ms during argument
normalization by clamping out-of-range model-provided values.
- Propagated the field through app-server v2
`ToolRequestUserInputParams`, app-server request forwarding, generated
TypeScript, and JSON schema fixtures.
- Updated app-server, core, protocol, and TUI call sites/tests so
omitted values preserve existing `None`/`null` behavior and coverage
verifies a `Some(60_000)` round trip.

## Verification

- `just test -p codex-app-server-protocol`
- `just test -p codex-core request_user_input`
- `just test -p codex-app-server request_user_input_round_trip`
- `just test -p codex-tui request_user_input`
- `just test -p codex-protocol`

codex-rs/core/src/codex_delegate_tests.rs

@@ -433,6 +433,7 @@ async fn delegated_mcp_guardian_abort_returns_synthetic_decline_answer() {
                 is_secret: false,
                 options: None,
             }],
+            auto_resolution_ms: None,
         },
         &cancel_token,
     )
@@ -476,6 +477,7 @@ async fn delegated_mcp_user_reviewer_returns_none_without_metadata() {
             is_secret: false,
             options: None,
         }],
+        auto_resolution_ms: None,
     };
     let response = maybe_auto_review_mcp_request_user_input(
         &parent_session,