- Replace _error_code_for_message() string matching with error_code attribute on exception classes
- Add error_code to all TwitterError subclasses (AuthenticationError, RateLimitError, etc.)
- Add InvalidInputError exception class
- TwitterAPIError derives error_code from HTTP status code automatically
- auth.py: use AuthenticationError instead of RuntimeError
- cli.py: catch (TwitterError, RuntimeError) for backward compat
- Extract _fetch_and_display_users() to deduplicate followers/following commands
- Add format_iso8601() to timeutil.py
- Add createdAtISO field to tweet and user profile serialization
- New test files: test_output.py, test_cache.py, test_timeutil.py
- Expand test_filter.py (topN, score mode, custom weights, empty input)
- Tests: 152 → 194 unit tests, all passing
- Fix auth.py subprocess script Windows Edge cookie path inconsistency
- Add timeutil.py for UTC→local time and relative time conversion
- Integrate time localization into formatter.py and serialization.py
- Add --output/-o option to show command for saving tweet detail as JSON
- Remove constants.py legacy aliases (USER_AGENT, SEC_CH_UA)
- Remove client.py backward-compat delegation methods and re-exports
- Update test imports to use parser module directly
