Support Codex Apps auth elicitations (#19193)

## Summary

- request URL-mode MCP elicitations when Codex Apps tool calls fail with
connector auth metadata
- route Codex Apps auth URL elicitations into the TUI app-link flow

## Test plan

- `just fmt`
- `cargo test -p codex-core mcp_tool_call::tests`
- `cargo test -p codex-mcp`
- `cargo test -p codex-tui bottom_pane::app_link_view::tests`
- `just fix -p codex-core`
- `just fix -p codex-mcp`
- `just fix -p codex-tui`

Also attempted broader local runs:

- `cargo test -p codex-core` fails in unrelated
config/request-permission/proxy-sensitive tests under the current Codex
Desktop environment.
- `cargo test -p codex-tui` fails in unrelated status
snapshots/trust-default tests because the ambient environment renders
workspace-write/network permission defaults.

codex-rs/tui/src/chatwidget/tests/app_server.rs

@@ -1,6 +1,42 @@
 use super::*;
 use pretty_assertions::assert_eq;
 
+#[tokio::test]
+async fn invalid_url_elicitation_is_declined() {
+    let (mut chat, _app_event_tx, mut rx, _op_rx) = make_chatwidget_manual_with_sender().await;
+    let thread_id = ThreadId::new();
+    chat.thread_id = Some(thread_id);
+
+    chat.handle_elicitation_request_now(
+        codex_app_server_protocol::RequestId::Integer(9),
+        codex_app_server_protocol::McpServerElicitationRequestParams {
+            thread_id: thread_id.to_string(),
+            turn_id: Some("turn-auth".to_string()),
+            server_name: "payments".to_string(),
+            request: codex_app_server_protocol::McpServerElicitationRequest::Url {
+                meta: None,
+                message: "Review the payment details to continue.".to_string(),
+                url: "http://payments.example/checkout/123".to_string(),
+                elicitation_id: "payment-123".to_string(),
+            },
+        },
+    );
+
+    assert_matches!(
+        rx.try_recv(),
+        Ok(AppEvent::SubmitThreadOp {
+            thread_id: op_thread_id,
+            op: Op::ResolveElicitation {
+                server_name,
+                request_id: codex_app_server_protocol::RequestId::Integer(9),
+                decision: codex_app_server_protocol::McpServerElicitationAction::Decline,
+                content: None,
+                meta: None,
+            },
+        }) if op_thread_id == thread_id && server_name == "payments"
+    );
+}
+
 #[tokio::test]
 async fn collab_spawn_end_shows_requested_model_and_effort() {
     let (mut chat, mut rx, _ops) = make_chatwidget_manual(/*model_override*/ None).await;