chore: migrate to pnpm v11, switch to nano-staged, add skills-npm (#111)

* chore: migrate to pnpm v11, switch to nano-staged, add skills-npm

- Bump packageManager to pnpm@11.1.3; rename onlyBuiltDependencies to allowBuilds
- Replace lint-staged with nano-staged
- Add skills-npm via prepare chain
- Set core.hooksPath to .githooks so simple-git-hooks works in worktrees

* ci: bump pnpm/action-setup to v6 for pnpm 11 global bin PATH fix

v4 leaves the v11 isolated global bin dir ($PNPM_HOME/bin) out of PATH,
breaking `pnpm i -g @antfu/ni`. v6 ships pnpm 11 support and the PATH fix.

.gitignore

@@ -1,5 +1,6 @@
 .cache
 .DS_Store
+.githooks
 .idea
 *.log
 *.tgz
@@ -8,4 +9,5 @@ dist
 lib-cov
 logs
 node_modules
+skills/npm-*
 temp