Add skills subcommand and fix npm metadata

New `impeccable skills` CLI with three subcommands:
- `skills help`: fetches and displays all 20 commands from the API
- `skills install`: delegates to `npx skills add pbakaus/impeccable`
- `skills update`: tries `npx skills update` first; if skills aren't
  managed by the skills CLI, downloads the universal bundle from
  impeccable.style and overwrites provider folders directly, with
  git-based modification detection and confirmation prompt

Also fixes npm metadata: homepage -> impeccable.style, license -> Apache-2.0

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

package.json

@@ -9,6 +9,7 @@
     "bin/",
     "source/skills/critique/scripts/detect-antipatterns.mjs",
     "source/skills/critique/scripts/detect-antipatterns-browser.js",
+    "lib/download-providers.js",
     "LICENSE"
   ],
   "dependencies": {
@@ -29,7 +30,8 @@
     "html",
     "cli"
   ],
-  "license": "SEE LICENSE FILE",
+  "license": "Apache-2.0",
+  "homepage": "https://impeccable.style",
   "repository": {
     "type": "git",
     "url": "git+https://github.com/pbakaus/impeccable.git"