Redo the Campus and Toxic Garden stage concepts #66

Problem

Campus is still 🟡 (the scaffold keeps disappearing) and Toxic Garden needs to stay outdoors with the collage palette. Later regions get visual direction only during the jam (decision 30).

Acceptance criteria

• Campus: flat side elevation, collage palette, the scaffold as a climb route
• Toxic Garden: outdoor corten beds under the highway bridge, no red liquid

Notes and dependencies

Stage concepts. Parked until the slice ships.

Verification

Owner review on the concept pages.