chore: close cleanup-stale-skill-installs task

Verified the user's `Remove-Item -Recurse -Force ~/.claude/skills/...`
ran cleanly:
  - 16 skills in ~/.claude/skills/, no duplicates
  - Old `wiki-maintainer` and `task-status-wiki` gone
  - New `using-wiki`, `using-tasks`, `setup-wiki`, `setup-tasks` present
  - context7 plugin confirmed live (mcp__plugin_context7_context7__*
    tools showed up after restart, legacy mcp__context7__* gone)

Removed the ⚪ block from .tasks/STATUS.md; logged in .wiki/log.md.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.tasks/STATUS.md

@@ -14,14 +14,6 @@ _Updated: 2026-04-28_
     🔵 Blocked    — waiting on external input
 -->
 
-## ⚪ [cleanup-stale-skill-installs] — remove old wiki-maintainer and task-status-wiki installs
-**Status:** ready
-**Where I stopped:** (not started)
-**Next action:** `rm -rf ~/.claude/skills/wiki-maintainer ~/.claude/skills/task-status-wiki` then verify only `using-wiki` and `using-tasks` remain
-**Branch:** (no branch — local cleanup)
-
----
-
 ## ⚪ [compress-dedup] — resolve compress vs caveman-compress duplication
 **Status:** ready
 **Where I stopped:** (not started) — noticed during initial migration that both skills ship identical `scripts/` subtrees (`compress.py`, `cli.py`, `detect.py`, `validate.py`, `benchmark.py`)