Build the canonical `/tower-defense/` route for the master `{{ skill:oneshot }}` catalog.

Project: `crest-alpha-origin`
Route: `tower-defense`
Deployment target: `https://crest-alpha-origin.pages.dev/tower-defense/`

Primary benchmark brief:
- 3D tower defense benchmark
- Buildable towers
- Waves and readable enemy behaviors
- Clear controls and legible HUD
- Keyboard and pointer support where practical
- Distinct, visually ambitious presentation
- No external images
- Reduced-motion fallback where applicable

Output contract:
- Write a single-file live artifact to `index.html`
- Write `artifact.json` with the canonical route metadata
- Keep the route self-contained inside this directory

Quality bar:
- Strong visual hierarchy and non-generic interface treatment
- Balanced play loop with economy, upgrades, and wave pacing
- Complete interaction states: start, active play, pause, victory, and failure
- Readable build/upgrade/sell controls and useful wave previewing