feat: integrate Changesets for multi-package npm publishing

Migrate from single-bundle CLI publishing to publishing all @paperclipai/*
packages individually via Changesets. This fixes the "Cannot find package
@paperclipai/server" error when installing from npm.

Changes:
- Add @changesets/cli with fixed versioning (all packages share version)
- Make 7 packages publishable (shared, adapter-utils, db, 3 adapters, server)
- Add build scripts, publishConfig, and files fields to all packages
- Mark @paperclipai/server as external in CLI esbuild config
- Simplify CLI importServerEntry() to use string-literal dynamic import
- Add generate-npm-package-json support for external workspace packages
- Create scripts/release.sh for one-command releases
- Remove old bump-and-publish.sh and version-bump.sh
- All packages start at version 0.2.0

Usage: ./scripts/release.sh patch|minor|major [--dry-run]

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

cli/package.json

@@ -1,6 +1,6 @@
 {
   "name": "paperclipai",
-  "version": "0.1.2",
+  "version": "0.2.0",
   "description": "Paperclip CLI — orchestrate AI agent teams to run a business",
   "type": "module",
   "bin": {
@@ -23,9 +23,13 @@
   "files": [
     "dist"
   ],
+  "publishConfig": {
+    "access": "public"
+  },
   "scripts": {
     "dev": "tsx src/index.ts",
-    "build": "tsc",
+    "build": "node --input-type=module -e \"import esbuild from 'esbuild'; import config from './esbuild.config.mjs'; await esbuild.build(config);\" && chmod +x dist/index.js",
+    "clean": "rm -rf dist",
     "typecheck": "tsc --noEmit"
   },
   "dependencies": {