[M1-S7] Annotate Rusty Creek collision: 3 chunks, clean and anomaly #55

Problem

Rusty Creek has art and a route graph but no collision. The maze is also the movement tutorial, so the layout has to teach jump, climb, ladders and the chair in that order.

Acceptance criteria

• .collision.json for left, center and right chunks, in both states
• Clean: the bridge walk with no enemies; anomaly: the maze with ladders, decks, hazards, spawns and the boss gate
• The route in route.json is reachable with the 28×76 body
• Placement order teaches jump → climb → ladders → chair

Notes and dependencies

Colours and scale: 04. Beats: 03 – Region 1 story beats. Suggested owner: Lex (level design, collision, encounters).

Verification

Overlay screenshot per chunk and state in the PR; the hero walks the route on the preview.