Fix four cron job issues: URL normalization, GitHub API resilience, log noise, cache TTL
- Strip trailing slashes from PDS URLs to prevent double-slash in xrpc paths
- Add User-Agent header to GitHub API requests and preserve etag on errors
- Suppress individual listRepos 404 logs, show summary count instead
- Add DNS (7d) and geo (30d) cache TTL to refresh stale enrichment data