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/src/demos/ManyBlocksDemo.vue

@@ -0,0 +1,25 @@
+<script setup lang="ts">
+import type { Node } from '@writekit';
+import { WritekitRoot } from '@writekit';
+import { h, makeWritekit, p } from '../lib';
+import Toolbar from '../Toolbar.vue';
+
+const blocks: Node[] = [];
+for (let i = 1; i <= 60; i++) {
+  if (i % 10 === 1)
+    blocks.push(h(2, `Section ${Math.ceil(i / 10)}`));
+  else
+    blocks.push(p(`Block ${i}: the quick brown fox jumps over the lazy dog.`));
+}
+
+const writekit = makeWritekit(blocks);
+</script>
+
+<template>
+  <section>
+    <h2>Many blocks</h2>
+    <p class="hint">60 blocks — test cross-block drag over a long range, ↑/↓ navigation, and Cmd/Ctrl+A (once = current block, twice = whole document).</p>
+    <Toolbar :writekit="writekit" />
+    <WritekitRoot :writekit="writekit" class="writekit scroll" />
+  </section>
+</template>