Initial release v0.1.0

Python parser for taskmark-spec markdown task files.

Features:
- Parse API: loads(), load() with link following
- Mutation API: update(), batch_update(), write_updates()
- Task states: open, done, cancelled, blocked
- Recurrence: daily, weekly, 2nd-tuesday, "every other week"
- Inheritance: heading → task, parent → subtask
- Explicit state machine with customizable transitions

Technical:
- Lark parser (Earley algorithm)
- Pendulum for timezone-aware dates
- 170 golden tests, 80% coverage threshold
- Python 3.11+, fully typed (py.typed)