ci(switch): skip fused build on fork pull requests

Keep ubuntu selftest for fork→canonical PRs; leave iOS build policy alone.

Co-authored-by: Cursor <cursoragent@cursor.com>

.github/workflows/ci.yml

@@ -145,7 +145,11 @@ jobs:
   switch-build:
     name: Switch fused build
     needs: switch-changes
-    if: needs.switch-changes.outputs.changed == 'true' && github.repository == 'bryanthaboi/gen1recomp'
+    if: >-
+      needs.switch-changes.outputs.changed == 'true'
+      && github.repository == 'bryanthaboi/gen1recomp'
+      && (github.event_name != 'pull_request'
+          || github.event.pull_request.head.repo.full_name == github.repository)
     runs-on: ["self-hosted", "macOS"]
     steps:
       - uses: actions/checkout@v7