fix: bundle skills directory into npm packages for runtime discovery

The claude-local, codex-local adapters and the server all resolve a
skills/ directory using __dirname-relative paths that only work inside
the monorepo.  When installed from npm the paths point outside the
package and cause ENOENT on readdir/readFile.

- Update both adapter execute.ts files to try a published-path
  candidate (../../skills from dist/) before falling back to the
  monorepo dev path (../../../../../skills from src/).
- Update server readSkillMarkdown() to try the published path first.
- Add "skills" to the files array in server, claude-local, and
  codex-local package.json so npm includes them.
- Update release.sh to copy the repo-root skills/ into each package
  before publish, and clean up after.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@paperclipai/server",
-  "version": "0.2.3",
+  "version": "0.2.4",
   "type": "module",
   "exports": {
     ".": "./src/index.ts"
@@ -18,7 +18,8 @@
   },
   "files": [
     "dist",
-    "ui-dist"
+    "ui-dist",
+    "skills"
   ],
   "scripts": {
     "dev": "tsx src/index.ts",