feat(core): dynamic custom frontmatter fields for CTF writeup metadata

- Add extra_fields JSONB column to documents table (migration 0003)
- CreateDocInput/UpdateDocInput: extraFields?: Record<string, string>
- parseFile: extracts non-standard frontmatter keys as extraFields
- stringifyFile: writes extraFields dynamically to YAML frontmatter
- toMeta: spreads extraFields from DB row into DocumentMeta
- DocForm: '+ Add field' UI for content creators to add any metadata
- API routes: splitPayload() separates standard vs custom fields
- Doc page: CustomFieldBadges dynamically renders any custom field
- Add db:migrate / db:push scripts + deploy workflow migration step
- Add CTF writeup template (content/writeups/ctf/template/)
- Add sample DEF CON writeup with event/challenge/category/difficulty/points
- Add @tailwindcss/typography for table rendering (prose classes)
- Add remark-gfm for GitHub Flavored Markdown table parsing

apps/web/app/api/docs/[...slug]/route.ts

@@ -17,6 +17,27 @@ function unauthorized() {
   return NextResponse.json({ ok: false, error: "Unauthorized" }, { status: 401 });
 }
 
+const STANDARD_FIELDS = new Set([
+  "title", "body", "type", "status",
+  "author", "tags", "createdAt", "updatedAt", "id", "path", "slug",
+]);
+
+function splitPayload(body: Record<string, unknown>): {
+  standard: Record<string, unknown>;
+  extraFields: Record<string, string>;
+} {
+  const standard: Record<string, unknown> = {};
+  const extraFields: Record<string, string> = {};
+  for (const [key, value] of Object.entries(body)) {
+    if (STANDARD_FIELDS.has(key)) {
+      standard[key] = value;
+    } else if (value !== undefined && value !== null) {
+      extraFields[key] = typeof value === "string" ? value : JSON.stringify(value);
+    }
+  }
+  return { standard, extraFields };
+}
+
 // PUT /api/docs/{slug...} — Update an existing document.
 export async function PUT(
   req: NextRequest,
@@ -35,7 +56,8 @@ export async function PUT(
   }
 
   try {
-    const doc = await updateDocument(fullSlug, body);
+    const { standard, extraFields } = splitPayload(body);
+    const doc = await updateDocument(fullSlug, { ...standard, extraFields } as any);
     return NextResponse.json({ ok: true, slug: doc.slug, doc });
   } catch (err) {
     const msg = err instanceof Error ? err.message : String(err);