build: migrate to pnpm (#86)

Yarn is outdated, lerna has less to offer. Pnpm becomes the best
solution for monorepos.

Here's publishing recipe

```sh
pnpm version-all 2.9.2
git add -A
git commit -m "2.9.2"
git tag 2.9.2
pnpm publish-all
```

Author: TrySound

lerna.json

@@ -1,16 +1,15 @@
 {
+  "packageManager": "pnpm@9.15.0",
   "private": true,
-  "workspaces": [
-    "packages/*"
-  ],
   "scripts": {
+    "version-all": "pnpm -r exec npm version",
+    "publish-all": "pnpm -r publish",
     "lint": "eslint packages --fix"
   },
   "devDependencies": {
     "@eslint/js": "^9.5.0",
     "eslint": "^9.5.0",
     "globals": "^15.6.0",
-    "lerna": "^2.5.1",
     "lint-staged": "^6.0.0",
     "yorkie": "^1.0.1"
   },

package.json

@@ -19,6 +19,6 @@
   },
   "homepage": "https://github.com/yyx990803/launch-editor#readme",
   "dependencies": {
-    "launch-editor": "^2.9.1"
+    "launch-editor": "workspace:^"
   }
 }

packages/launch-editor-middleware/package.json

@@ -0,0 +1,2 @@
+packages:
+  - "packages/*"