feat(editor): eslint/tsconfig migration + type fixes

@robonen/editor: migrate to eslint flat config + composite tsconfig; fix
convergence test type annotations.

vue/editor/src/view/primitive/getRawChildren.ts

@@ -0,0 +1,43 @@
+import type { VNode } from 'vue';
+import { Comment, Fragment } from 'vue';
+import { PatchFlags } from '@vue/shared';
+
+/**
+ * Recursively extracts and flattens VNodes from potentially nested Fragments
+ * while filtering out Comment nodes. Local copy of the primitives helper to keep
+ * `@robonen/editor` self-contained.
+ *
+ * @param children - Array of VNodes to process
+ * @returns Flattened array of non-Comment VNodes
+ */
+export function getRawChildren(children: VNode[]): VNode[] {
+  const result: VNode[] = [];
+  flatten(children, result);
+  return result;
+}
+
+function flatten(children: VNode[], result: VNode[]): void {
+  let keyedFragmentCount = 0;
+  const startIdx = result.length;
+
+  for (let i = 0, len = children.length; i < len; i++) {
+    const child = children[i]!;
+
+    if (child.type === Fragment) {
+      if (child.patchFlag & PatchFlags.KEYED_FRAGMENT) {
+        keyedFragmentCount++;
+      }
+
+      flatten(child.children as VNode[], result);
+    }
+    else if (child.type !== Comment) {
+      result.push(child);
+    }
+  }
+
+  if (keyedFragmentCount > 1) {
+    for (let i = startIdx; i < result.length; i++) {
+      result[i]!.patchFlag = PatchFlags.BAIL;
+    }
+  }
+}