Fix deployment: remove stale 'core' team references and add validation

PR #17 removed the 'core' group but left references in repoAccess.ts,
causing deployments to fail since Nov 25th.

Changes:
- Remove 'core' team references from 6 repositories in repoAccess.ts
- Replace with 'core-maintainers' to maintain equivalent permissions
- Add scripts/validate-config.ts to validate all team references
- Add pre-commit hook to run validation on config changes
- Add npm run validate script

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

.pre-commit-config.yaml

@@ -15,3 +15,10 @@ repos:
         language: system
         pass_filenames: false
         files: \.(ts|tsx)$
+
+      - id: validate-config
+        name: Validate team references
+        entry: npm run validate
+        language: system
+        pass_filenames: false
+        files: ^src/config/