fix: Update workflow permissions to allow git push

- Change contents permission from 'read' to 'write'
- Fixes 403 permission denied error in commit step
- Allows feature tracker database updates to be persisted
- Resolves final remaining issue in #224

Previous runs showed MCP connectivity and feature discovery working,
but failing on git push due to insufficient permissions.

Author: lgallard

.github/workflows/feature-discovery.yml

@@ -30,7 +30,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 15
     permissions:
-      contents: read
+      contents: write
       issues: write
       actions: read
       id-token: write