feat(writekit): rename @robonen/editor to @robonen/writekit

Rename the rich-text editor package and all Editor* exports to Writekit*;
remove the old vue/editor tree.

vue/writekit/playground/package.json

@@ -0,0 +1,23 @@
+{
+  "name": "@robonen/writekit-playground",
+  "version": "0.0.0",
+  "private": true,
+  "license": "Apache-2.0",
+  "description": "Minimal playground for @robonen/writekit — eyeball, debug, hack on hypotheses",
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "vite build",
+    "preview": "vite preview"
+  },
+  "dependencies": {
+    "@robonen/writekit": "workspace:*",
+    "vue": "catalog:"
+  },
+  "devDependencies": {
+    "@robonen/tsconfig": "workspace:*",
+    "@vitejs/plugin-vue": "^6.0.7",
+    "vite": "^8.0.16",
+    "vue-tsc": "^3.3.4"
+  }
+}