Remove directory linking and simplify to file-only symlinks

Major rewrite to simplify cfgman's core functionality:
- Remove directory linking feature - now creates individual file symlinks only
- Simplify configuration to basic source/target mappings
- Refactor into focused modules with clean separation of concerns
- Extract common functionality (file ops, git ops, validation, etc.)
- Improve error handling and user feedback throughout
- Add comprehensive test coverage for all new modules

Switch to standard pre-1.0 versioning scheme

Changed from beta versioning (v1.0.0-beta.x) to standard semantic
versioning for pre-release software (v0.x.x). Updated changelog to
follow Keep a Changelog standard and added changelog guidelines.

Fix orphan command issues

- Fix misleading message order in orphan command (now shows correct sequence)
- Remove redundant confirmation messages when orphaning directories
- Fix untracked files not being deleted from repository after orphaning
- Rename removeFromGit to removeFromRepository for clarity
- Add comprehensive test for orphaning untracked files

Initial commit

A dotfile management tool that creates intelligent symlinks
between configuration files in a git repository and their expected locations.

Features:
- Directory-based operation (like git, npm, make)
- Simple .cfgman.json configuration format
- Built-in gitignore-style pattern matching
- Flexible link mappings with file/directory-level control
- Safety features: dry-run mode, confirmations, cross-repo protection
- Zero external dependencies

See CHANGELOG.md for full feature list.