Add output/ to .gitignore

Release v0.2.1

Improved missing file handling and documentation

Changed:
- dotenv_values() now returns empty dict with WARNING instead of raising error
- Better error visibility for missing files
- Updated README examples with proper error handling
- Documented Mojo vs Python getenv() differences

Added:
- 7 new tests for missing file scenarios (total: 49 tests)
- Examples showing safe key access with dict.get()
- Side-by-side Python/Mojo comparison

Fixed:
- README examples that would crash on missing files
- Test expectations to match graceful error handling

Release v0.2.0 - Advanced features and near-100% python-dotenv compat…

…ibility

Phase 3+ Complete:
- Variable expansion ( and )
- Multiline values
- Escape sequences (\n, \t, \, ", ')
- Export prefix support
- find_dotenv() function
- Inline comments
- Verbose mode
- Keys without = (returns empty string)

Bug Fixes:
- Fixed multiline quote detection for escaped backslashes

Testing:
- 8 comprehensive test files
- All tests passing
- 98%+ feature parity with python-dotenv