Start cloud threads with the local GitHub project (#60007)

## What changed

Pass the local project's GitHub origin to cloud prewarming so new cloud threads can provision a repository checkout. Preserve the attached local project when switching backends and resolve its origin for each thread start.

Normalize supported GitHub origins to credential-free HTTPS URLs and select a repository-specific cloud working directory. Unsupported origins retain the blank environment behavior. Keep project metadata outside the app-server wire protocol, and fix HTTP Git URL parsing so query strings and fragments cannot be mistaken for authority text.

## Testing

Add coverage for project routing, origin normalization and rejection, managed environment encoding, local project retention, and Git URL credential stripping.

GitOrigin-RevId: 5859769965faf060461ccc1cbb3fd48f8e2f2155

codex-rs/app-server-client/src/cloud.rs

@@ -19,6 +19,12 @@ use tokio::sync::oneshot;
 /// Unsupported operations must return an explicit error; they must not claim success.
 pub enum CloudOperation {
     Request(Box<ClientRequest>),
+    /// Host project metadata stays on the private transport, outside the app-server wire.
+    StartProjectThread {
+        request_id: RequestId,
+        params: Box<codex_app_server_protocol::ThreadStartParams>,
+        project: codex_cloud_client::ProjectEnvironment,
+    },
     SubmitUserMessage(Box<TurnStartParams>),
     Notify(ClientNotification),
     Resolve {
@@ -124,6 +130,20 @@ impl CloudClient {
 }
 
 impl CloudRequestHandle {
+    pub(crate) async fn start_project_thread(
+        &self,
+        request_id: RequestId,
+        params: codex_app_server_protocol::ThreadStartParams,
+        project: codex_cloud_client::ProjectEnvironment,
+    ) -> io::Result<RequestResult> {
+        self.send(CloudOperation::StartProjectThread {
+            request_id,
+            params: Box::new(params),
+            project,
+        })
+        .await
+    }
+
     /// Submit once with a stable message ID and saved thread settings. The server
     /// starts or steers; an error can mean admission is unknown. Never auto-resend.
     pub async fn submit_user_message(