Admin: write blog posts and manage images

A Posts page lists every post with Write a post: title, topic, kind,
date, summary, a cover picked from the vault or uploaded, the pages it is
about, the Markdown body with a rendered preview, and Save draft or
Publish. An Images page uploads several images into an _attachments
folder, shows which notes use each one, copies its embed line, and
deletes unused ones. The content service gains the attachment list,
upload and delete endpoints behind the editor and admin tokens.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012aSbo2D1qP8cMFQCykf7kx

services/admin/src/layout.ts

@@ -12,6 +12,8 @@ const nav: [string, string][] = [
   ["/inbox", "Inbox"],
   ["/notes", "Notes"],
   ["/drafts", "Drafts"],
+  ["/posts", "Posts"],
+  ["/images", "Images"],
   ["/capture", "Capture"],
   ["/store", "Store"],
   ["/problems", "Problems"],
@@ -29,6 +31,7 @@ export function layout(p: { title: string; path: string; held: number; inbox?: n
 <link rel="preconnect" href="https://fonts.googleapis.com">
 <link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=Cinzel:wght@600&family=Montserrat:wght@400;600;700&display=swap">
 <link rel="stylesheet" href="/admin.css">
+<script src="/admin.js" defer></script>
 </head>
 <body>
 <header class="top">