Introduces the GoalDecomposer class that bridges mission.strategy + plugin
capabilities into concrete, weighted Task objects. Each Task has a target
screen, budget, weight, and human-readable intent.
Key design decisions:
- Pure logic, zero LLM/device dependencies
- Strategy weights (aggressive_growth, community_builder, etc.) drive selection
- Plugins declare which screens they operate on (multi-screen map)
- Screens need BOTH an action route AND active plugin to be viable
- Frozen dataclass ensures Task immutability
12/12 TDD tests passing.