[codex] Add OpenAI Developers to tool suggest allowlist (#21423)

## Summary

Add `openai-developers@openai-curated` to
`TOOL_SUGGEST_DISCOVERABLE_PLUGIN_ALLOWLIST` so the OpenAI Developers
plugin can be surfaced through tool suggestions once it is available in
the Built by OpenAI marketplace.

Update the discoverable plugin test fixture to assert the plugin is
returned from the curated marketplace allowlist path.

## Validation

- `cargo fmt --check` passed; rustfmt emitted the existing
stable-channel warnings about `imports_granularity`.
- `cargo test -p codex-core
list_tool_suggest_discoverable_plugins_returns_uninstalled_curated_plugins`
passed.

codex-rs/core-plugins/src/lib.rs

@@ -26,6 +26,7 @@ pub const TOOL_SUGGEST_DISCOVERABLE_PLUGIN_ALLOWLIST: &[&str] = &[
     "gmail@openai-curated",
     "google-calendar@openai-curated",
     "google-drive@openai-curated",
+    "openai-developers@openai-curated",
     "canva@openai-curated",
     "teams@openai-curated",
     "sharepoint@openai-curated",

codex-rs/core/src/plugins/discoverable_tests.rs

@@ -19,7 +19,7 @@ use tracing_test::internal::MockWriter;
 async fn list_tool_suggest_discoverable_plugins_returns_uninstalled_curated_plugins() {
     let codex_home = tempdir().expect("tempdir should succeed");
     let curated_root = curated_plugins_repo_path(codex_home.path());
-    write_openai_curated_marketplace(&curated_root, &["sample", "slack"]);
+    write_openai_curated_marketplace(&curated_root, &["sample", "slack", "openai-developers"]);
     write_plugins_feature_config(codex_home.path());
 
     let config = load_plugins_config(codex_home.path()).await;
@@ -29,16 +29,28 @@ async fn list_tool_suggest_discoverable_plugins_returns_uninstalled_curated_plug
 
     assert_eq!(
         discoverable_plugins,
-        vec![DiscoverablePluginInfo {
-            id: "slack@openai-curated".to_string(),
-            name: "slack".to_string(),
-            description: Some(
-                "Plugin that includes skills, MCP servers, and app connectors".to_string(),
-            ),
-            has_skills: true,
-            mcp_server_names: vec!["sample-docs".to_string()],
-            app_connector_ids: vec!["connector_calendar".to_string()],
-        }]
+        vec![
+            DiscoverablePluginInfo {
+                id: "openai-developers@openai-curated".to_string(),
+                name: "openai-developers".to_string(),
+                description: Some(
+                    "Plugin that includes skills, MCP servers, and app connectors".to_string(),
+                ),
+                has_skills: true,
+                mcp_server_names: vec!["sample-docs".to_string()],
+                app_connector_ids: vec!["connector_calendar".to_string()],
+            },
+            DiscoverablePluginInfo {
+                id: "slack@openai-curated".to_string(),
+                name: "slack".to_string(),
+                description: Some(
+                    "Plugin that includes skills, MCP servers, and app connectors".to_string(),
+                ),
+                has_skills: true,
+                mcp_server_names: vec!["sample-docs".to_string()],
+                app_connector_ids: vec!["connector_calendar".to_string()],
+            },
+        ]
     );
 }