fix: remove duplicate wasteland skill (now in marketplace) (#13)

The wasteland skill file lived in two places:
- web/public/wasteland-skill.md (this repo)
- plugins/wasteland/skills/wasteland/SKILL.md (gastownhall/marketplace)

This caused drift — daily-ops commands and fork API fixes landed here
but never reached marketplace where users actually install from.

Removes the local copy, the /skill page component, and its route.
The nav "skill" link already points to the marketplace repo.

See: gastownhall/marketplace#3

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: julianknutsen