Refactor to static markdown (remove Supabase backend) + self-host build

Posts now read from data/posts/*.md via gray-matter + remark; authors derived
from posts. Removes admin dashboard, comments, subscriptions, and all Supabase
usage. Adds Dockerfile (Next.js standalone) + Gitea Actions CI. output: standalone.

lib/authors.ts

@@ -0,0 +1,57 @@
+import { getSortedPostsData, getPostsByAuthor } from "@/lib/posts";
+import { PostMetadata } from "@/types";
+
+export interface AuthorSummary {
+  name: string;
+  slug: string;
+  postCount: number;
+  // No bio data is available in the static build; these remain optional.
+  bio?: string;
+  x_link?: string;
+  fb_link?: string;
+  insta_link?: string;
+  pfp_link?: string;
+}
+
+export interface AuthorWithPosts extends AuthorSummary {
+  posts: PostMetadata[];
+}
+
+/**
+ * Derive the list of authors from the posts' frontmatter.
+ * The author `slug` is the author name itself, which is what
+ * `getPostsByAuthor` filters on and what the `[author]` route uses.
+ */
+export async function getAllAuthors(): Promise<AuthorSummary[]> {
+  const posts = await getSortedPostsData();
+
+  const counts = new Map<string, number>();
+  for (const post of posts) {
+    if (!post.author) continue;
+    counts.set(post.author, (counts.get(post.author) || 0) + 1);
+  }
+
+  return Array.from(counts.entries())
+    .map(([name, postCount]) => ({
+      name,
+      slug: name,
+      postCount,
+    }))
+    .sort((a, b) => a.name.localeCompare(b.name));
+}
+
+export async function getAuthor(
+  name: string,
+): Promise<AuthorWithPosts | null> {
+  const posts = await getPostsByAuthor(name);
+  if (posts.length === 0) {
+    return null;
+  }
+
+  return {
+    name,
+    slug: name,
+    postCount: posts.length,
+    posts,
+  };
+}