pacwich 0.3.0 - Shell completions

Added

• Project-aware completion support for the globally installed CLI's pacwich binary
  • New CLI command: pacwich completion
    • No args: Print help guide for setup options
    • Pass install: Attempts to write installation into shell config
    • See documentation for full syntax
    • Quick tip for usage placed in all global install docs
  • AI doc features:
    • Overview doc: added installation section with completion setup tip