Implements tickets #237 and #238 for Sprint 3:
- Add pathfinding crate dependency for A* algorithm
- PathRequest component triggers compute_paths system which uses
cardinal-neighbor A* with manhattan distance heuristic
- ComputedPath component with step navigation (next_step, advance,
is_complete) and PathBlocked marker for no-route cases
- MovementSpeed component throttles NPC movement (ticks_per_step)
- follow_paths system advances NPCs along computed paths, creating
MoveIntent per step; cleanup_path_blocked removes markers after
one tick
- System ordering: input → compute_paths → follow_paths →
validate_movement → cleanup_path_blocked → advance_tick
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
jpmschweitzerandClaude Opus 4.6
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