docs(claude): install manual skills at top level (#2160)

* docs(claude): install manual skills at top level

* test(docs): guard Claude manual skill install path

* test(docs): detect PowerShell/$HOME nested skill-install paths

Address CodeRabbit on #2160: the nested-path regression guard only matched
Unix `mkdir`/`cp` with `~`, so a reintroduced PowerShell `Copy-Item ...
$HOME/.claude/skills/ecc` (or backslash-separated) form would have slipped
through. Extend the pattern to also cover `Copy-Item`/`New-Item` (and the
`md`/`copy`/`cpi` aliases), accept `$HOME` as an alternative to `~`, allow both
`/` and `\` separators, and match case-insensitively.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

README.md

@@ -903,13 +903,15 @@ cp -r rules/arkts ~/.claude/rules/ecc/
 
 # Copy skills first (primary workflow surface)
 # Recommended (new users): core/general skills only
-mkdir -p ~/.claude/skills/ecc
-cp -r .agents/skills/* ~/.claude/skills/ecc/
-cp -r skills/search-first ~/.claude/skills/ecc/
+mkdir -p ~/.claude/skills
+cp -r .agents/skills/* ~/.claude/skills/
+cp -r skills/search-first ~/.claude/skills/
+# Claude Code loads skills only from direct children of ~/.claude/skills.
+# Do not nest manual installs under ~/.claude/skills/ecc/.
 
 # Optional: add niche/framework-specific skills only when needed
 # for s in django-patterns django-tdd laravel-patterns springboot-patterns quarkus-patterns; do
-# cp -r skills/$s ~/.claude/skills/ecc/
+# cp -r skills/$s ~/.claude/skills/
 # done
 
 # Optional: keep maintained slash-command compatibility during migration