fix(24-01): parse JSON response in recording REST functions

The startRecording, stopRecording, and getRecordingPromise functions
were returning the raw Response object instead of the parsed JSON data.
This caused recording.id to be undefined, leading to the C++ client
crash with "Assertion failed: (!clientId.isEmpty())".

- Add .json() parsing before resolving the Promise
- Fixes crash when clicking Start Recording

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

jam-ui/src/helpers/rest.js

@@ -755,7 +755,8 @@ export const startRecording = (options) => {
       method: 'POST',
       body: JSON.stringify(options)
     })
-      .then(response => resolve(response))
+      .then(response => response.json())
+      .then(data => resolve(data))
       .catch(error => reject(error));
   });
 };
@@ -767,7 +768,8 @@ export const stopRecording = (options) => {
       method: 'POST',
       body: JSON.stringify(rest)
     })
-      .then(response => resolve(response))
+      .then(response => response.json())
+      .then(data => resolve(data))
       .catch(error => reject(error));
   });
 };
@@ -776,7 +778,8 @@ export const getRecordingPromise = (options) => {
   const { id } = options;
   return new Promise((resolve, reject) => {
     apiFetch(`/recordings/${id}`)
-      .then(response => resolve(response))
+      .then(response => response.json())
+      .then(data => resolve(data))
       .catch(error => reject(error));
   });
 };