Add an app-server API for reading app metadata (#33651)

## What changed

- Add the experimental `app/read` request for fetching metadata for up to 100
  app IDs, with optional display-only tool summaries.
- Preserve first-request order while deduplicating IDs, and report unknown or
  unauthorized apps as partial misses.
- Cache metadata by backend and ChatGPT account/workspace identity, refetch
  metadata-only entries when tools are requested, and preserve cached records
  when a backend request fails.

## Testing

- Cover request serialization, ordering, deduplication, partial misses, caching,
  tool-summary refetches, backend failures, cache isolation, and the ID limit.

GitOrigin-RevId: 55fc3281d99291e76d6c4a581e8d11569d3cb1ac

codex-rs/app-server-protocol/src/protocol/v2/apps.rs

@@ -131,6 +131,50 @@ fn non_empty_category(category: Option<&str>) -> Option<String> {
     }
 }
 
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+/// EXPERIMENTAL - read metadata for specific apps/connectors.
+pub struct AppsReadParams {
+    /// App ids to read. The server accepts at most 100 ids and deduplicates repeated ids while
+    /// preserving their first-request order.
+    pub app_ids: Vec<String>,
+    /// When true, include display-only public tool summaries in the returned metadata.
+    #[serde(default, skip_serializing_if = "std::ops::Not::not")]
+    pub include_tools: bool,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+/// EXPERIMENTAL - metadata returned by app/read.
+pub struct AppToolSummary {
+    pub name: String,
+    pub title: Option<String>,
+    pub description: String,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+/// EXPERIMENTAL - metadata returned by app/read.
+pub struct ConnectorMetadata {
+    pub id: String,
+    pub name: String,
+    pub description: Option<String>,
+    pub icon_url: Option<String>,
+    pub tool_summaries: Option<Vec<AppToolSummary>>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+/// EXPERIMENTAL - app/read response.
+pub struct AppsReadResponse {
+    pub apps: Vec<ConnectorMetadata>,
+    pub missing_app_ids: Vec<String>,
+}
+
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
 #[serde(rename_all = "camelCase")]
 #[ts(export_to = "v2/")]