Importer for ProPresenter's protobuf-encoded `Macros` document. Exposes
each macro's UUID and name plus the collections that group them.
- src/MacroLibrary.php: top-level wrapper indexed by UUID and name
- src/Macro.php, src/MacroCollection.php: per-entry wrappers
- src/MacrosFileReader.php: file -> MacroLibrary entry point
- bin/parse-macros.php: CLI listing macros and collections
- tests/MacrosFileReaderTest.php: 10 tests against reference sample
- doc/api/macros.md: API reference, plus INDEX/keywords updates
