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/features/src/lib.rs

@@ -204,6 +204,8 @@ pub enum Feature {
     CollaborationModes,
     /// Route MCP tool approval prompts through the MCP elicitation request path.
     ToolCallMcpElicitation,
+    /// Prompt Codex Apps connector auth failures through MCP URL elicitations.
+    AuthElicitation,
     /// Enable personality selection in the TUI.
     Personality,
     /// Enable native artifact tools.
@@ -1045,6 +1047,12 @@ pub const FEATURES: &[FeatureSpec] = &[
         stage: Stage::Stable,
         default_enabled: true,
     },
+    FeatureSpec {
+        id: Feature::AuthElicitation,
+        key: "auth_elicitation",
+        stage: Stage::UnderDevelopment,
+        default_enabled: false,
+    },
     FeatureSpec {
         id: Feature::Personality,
         key: "personality",

codex-rs/features/src/tests.rs

@@ -247,6 +247,16 @@ fn tool_call_mcp_elicitation_is_stable_and_enabled_by_default() {
     assert_eq!(Feature::ToolCallMcpElicitation.default_enabled(), true);
 }
 
+#[test]
+fn auth_elicitation_is_under_development() {
+    assert_eq!(Feature::AuthElicitation.stage(), Stage::UnderDevelopment);
+    assert_eq!(Feature::AuthElicitation.default_enabled(), false);
+    assert_eq!(
+        feature_for_key("auth_elicitation"),
+        Some(Feature::AuthElicitation)
+    );
+}
+
 #[test]
 fn remote_control_is_under_development() {
     assert_eq!(Feature::RemoteControl.stage(), Stage::UnderDevelopment);