Preserve runner process start time across controller recovery

Use the verified remote process marker and adopted process identity when reporting runner process metadata, rather than the creation time of a replacement controller transport.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

server/src/services/native-runtime/native-session-executor.test.ts

@@ -341,6 +341,7 @@ describe("remote runner process supervision", () => {
       startedAt: "2026-09-06T00:00:00.000Z",
     });
     expect(handle.child.pid).toBe(4321);
+    expect(handle.startedAt).toBe("2026-09-06T00:00:00.000Z");
 
     expect(handle.child.kill("SIGKILL")).toBe(true);
     await vi.waitFor(() =>

server/src/services/native-runtime/native-session-executor.ts

@@ -6362,7 +6362,11 @@ export function createRemoteRunnerProcessLauncher(input: {
         };
       }
     })();
-    return { child, completion };
+    return {
+      child,
+      completion,
+      get startedAt() { return launchedIdentity?.startedAt; },
+    };
   };
 }