feat(lesson-preparation): add anchor canvas design, new blocks, and textbook content node

- Add anchor injector for canvas-based anchor positioning

- Add new block components: blackboard, homework, import, key-point, new-teaching, objective, summary

- Add textbook content node for React Flow canvas

- Update actions (kp, publish, main), data-access (templates, versions, main)

- Update editor, node-editor, block-renderer, and picker components

- Update schema, types, hooks, and lib utilities (document-migration, node-summary, rf-mappers)

src/modules/lesson-preparation/data-access-templates.ts

@@ -96,10 +96,12 @@ export async function saveAsTemplate(input: {
   if (plan.length === 0) throw new LessonPlanDataError("NOT_FOUND");
 
   const doc = normalizeDocument(plan[0].content);
-  const skeleton: TemplateBlockSkeleton[] = doc.nodes.map((b) => ({
-    type: b.type,
-    title: b.title,
-  }));
+  const skeleton: TemplateBlockSkeleton[] = doc.nodes
+    .filter((b): b is import("./types").LessonPlanNode => b.type !== "textbook_content")
+    .map((b) => ({
+      type: b.type,
+      title: b.title,
+    }));
 
   const templateId = createId();
   await db.insert(lessonPlanTemplates).values({