Increase neural connectivity test timeout to 240 minutes

The CI-optimized neural connectivity validation step was timing out at
120 minutes. Bump to 240 to give it more headroom while the underlying
load behaviour is investigated.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: Robbie1977

.github/workflows/test_vfb_connect.yml

@@ -270,7 +270,7 @@ jobs:
           python -m pip install -r .github/workflows/requirements.txt
           
       - name: Run essential neural connectivity validation (CI-optimized)
-        timeout-minutes: 120
+        timeout-minutes: 240
         env:
           VFB_CI_MODE: true
           VFB_LOAD_LIMIT: 3