refactor: move read queries into server-only lib/data and render post stats on the server

Reads no longer live in "use server" files (which made them public
endpoints). /notes stats come from one cached query pair rendered on the
server; the post page comment count streams in as a dynamic hole.
revalidateTag("views"/"comments") now invalidates the cached stats.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

lib/data/comments.ts

@@ -0,0 +1,58 @@
+import "server-only";
+import { desc, eq, sql } from "drizzle-orm";
+
+import { db } from "@/lib/db";
+import * as schema from "@/lib/db/schema";
+
+export type CommentWithUser = typeof schema.comment.$inferSelect & {
+  user: Pick<typeof schema.user.$inferSelect, "id" | "name" | "image">;
+};
+
+/**
+ * Retrieves all comments for a given slug, newest first, with each author's public profile fields
+ */
+export const getComments = async (pageSlug: string): Promise<CommentWithUser[]> => {
+  try {
+    // Fetch all comments for the page with user details
+    const commentsWithUsers = await db
+      .select()
+      .from(schema.comment)
+      .innerJoin(schema.user, eq(schema.comment.userId, schema.user.id))
+      .where(eq(schema.comment.pageSlug, pageSlug))
+      .orderBy(desc(schema.comment.createdAt));
+
+    return commentsWithUsers.map(({ comment, user }) =>
+      Object.assign(comment, {
+        user: {
+          // we're namely worried about keeping the user's email private here, but nothing sensitive is stored in the db
+          id: user.id,
+          name: user.name,
+          image: user.image,
+        },
+      }),
+    );
+  } catch (error) {
+    console.error("[data/comments] error fetching comments:", error);
+    // Return empty array instead of throwing during prerendering
+    return [];
+  }
+};
+
+/**
+ * Retrieves the number of comments for a given slug (uncached -- call from inside a <Suspense> boundary)
+ */
+export const getCommentCount = async (slug: string): Promise<number> => {
+  try {
+    const result = await db
+      .select({
+        count: sql<number>`cast(count(${schema.comment.id}) as int)`,
+      })
+      .from(schema.comment)
+      .where(eq(schema.comment.pageSlug, slug));
+
+    return result[0]?.count ?? 0;
+  } catch (error) {
+    console.error("[data/comments] error fetching comment count:", error);
+    return 0;
+  }
+};