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/protocol/src/request_permissions.rs

@@ -0,0 +1,30 @@
+use crate::models::PermissionProfile;
+use schemars::JsonSchema;
+use serde::Deserialize;
+use serde::Serialize;
+use ts_rs::TS;
+
+#[derive(Debug, Clone, Deserialize, Serialize, PartialEq, Eq, JsonSchema, TS)]
+pub struct RequestPermissionsArgs {
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub reason: Option<String>,
+    pub permissions: PermissionProfile,
+}
+
+#[derive(Debug, Clone, Deserialize, Serialize, PartialEq, Eq, JsonSchema, TS)]
+pub struct RequestPermissionsResponse {
+    pub permissions: PermissionProfile,
+}
+
+#[derive(Debug, Clone, Deserialize, Serialize, PartialEq, Eq, JsonSchema, TS)]
+pub struct RequestPermissionsEvent {
+    /// Responses API call id for the associated tool call, if available.
+    pub call_id: String,
+    /// Turn ID that this request belongs to.
+    /// Uses `#[serde(default)]` for backwards compatibility.
+    #[serde(default)]
+    pub turn_id: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub reason: Option<String>,
+    pub permissions: PermissionProfile,
+}