Add request permissions tool (#13092)

Adds a built-in `request_permissions` tool and wires it through the
Codex core, protocol, and app-server layers so a running turn can ask
the client for additional permissions instead of relying on a static
session policy.

The new flow emits a `RequestPermissions` event from core, tracks the
pending request by call ID, forwards it through app-server v2 as an
`item/permissions/requestApproval` request, and resumes the tool call
once the client returns an approved subset of the requested permission
profile.

codex-rs/mcp-server/src/codex_tool_runner.rs

@@ -367,6 +367,7 @@ async fn run_codex_tool_session_inner(
                     | EventMsg::UndoCompleted(_)
                     | EventMsg::ExitedReviewMode(_)
                     | EventMsg::RequestUserInput(_)
+                    | EventMsg::RequestPermissions(_)
                     | EventMsg::DynamicToolCallRequest(_)
                     | EventMsg::DynamicToolCallResponse(_)
                     | EventMsg::ContextCompacted(_)