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/interactive.ts

@@ -0,0 +1,11 @@
+/**
+ * Whether a node is (inside) an atom's interactive control — a form field or a
+ * `contenteditable="false"` island. Events from these must NOT be treated as
+ * editor input: e.g. typing in an image's caption `<input>` bubbles up to the
+ * single contenteditable, and without this guard the editor would re-sync a text
+ * block and yank the caret to the start of the document.
+ */
+export function isInteractiveTarget(node: EventTarget | null): boolean {
+  return node instanceof Element
+    && node.closest('input, textarea, select, button, [contenteditable="false"]') !== null;
+}