fix: require explicit acknowledgment for wildcard write permission bypass

SECURITY FIX: Addresses authorization_bypass vulnerability (LOW severity)

The allowed_non_write_users='*' configuration previously bypassed write
permission checks for all users with only a warning. This created a
security misconfiguration risk.

Changes:
- Added new input 'bypass_write_permission_check_acknowledgment' required
  when using wildcard (*)
- Modified checkWritePermissions() to throw error if wildcard used without
  explicit acknowledgment flag
- Updated all documentation (security.md, usage.md) with new requirement
- Updated example workflows to include acknowledgment flag
- Added tests for new validation behavior

This prevents accidental security misconfigurations while maintaining the
feature for intentional use cases like issue triage workflows.

Affected file: src/github/validation/permissions.ts:27
Category: authorization_bypass
Severity: LOW

examples/issue-triage.yml

@@ -26,4 +26,5 @@ jobs:
 
           anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}
           allowed_non_write_users: "*" # Required for issue triage workflow, if users without repo write access create issues
+          bypass_write_permission_check_acknowledgment: true # Required when using wildcard
           github_token: ${{ secrets.GITHUB_TOKEN }}