refactor: update cursor request handling and improve parent request management

- Changed `run_id` to `request_id` in `CursorParent` struct for clarity.
- Enhanced the `prepare` function to handle parent requests asynchronously, ensuring proper error handling for active runs.
- Updated database interactions to include `cursor_request_id` for better tracking of requests.
- Added tests to verify the behavior of reused cursor request IDs and their mapping to distinct executions.

server/tests/runtime_modes.rs

@@ -117,7 +117,7 @@ async fn unchanged_request_context_is_not_repeated_and_preserves_the_provider_pr
     };
     assert_eq!(
         request.history[1].message_id,
-        "runtime:run-request:ask-request"
+        "runtime:cursor:user:wire-user"
     );
     assert!(!request.prompt.instructions.contains("workspace rule"));
     assert!(!request.prompt.instructions.contains("<mcp_meta_tools>"));