Add last_crawled timestamp tracking to fix fetchSnapshotsFromHistory()
infinite loop when SkipIdenticalContent=true. Now tracks actual crawl
attempts separately from content changes via database DEFAULT timestamps.
- Implement whitelist package for filtering URLs
- Support pattern matching for allowed URLs
- Add URL validation against whitelist patterns
- Include test cases for whitelist functionality
- Replace zerolog with Go's standard slog package
- Add ColorHandler for terminal color output
- Add context-aware logging system
- Format attributes on the same line as log messages
- Use green color for INFO level logs
- Set up context value extraction helpers
