Add CLI, config file support, and configurable lookback key

- Add clap-based CLI with comprehensive help
- Add TOML config support (~/.config/claude-chill.toml)
- Add key_parser for user-friendly key bindings ([ctrl][shift][j])
- Change default lookback key to Ctrl+Shift+J
- Remove unused modules (analyzer, output_processor, script_parser)
- Add MIT LICENSE file
- Add disclaimer to README

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.gitignore

@@ -19,3 +19,4 @@ target
 #  and can be added to the global gitignore or merged into this file.  For a more nuclear
 #  option (not recommended) you can uncomment the following to ignore the entire idea folder.
 #.idea/
+.claude