feat: keep the archive-fetching tooling on a branch of its own

The scripts and docs for fetching from Instagram now live here rather than on
main, which is the branch published to GitHub. They carry things that do not
belong in a public repo: the fetch host's public IP, the browser profile path
the cookie is read from, the NAS archive path, and the list of accounts being
archived.

This branch is a superset of main — the viewer plus the tooling — so it can
take main's changes by merging, and the npm script and CLAUDE.md entries that
reference the tooling live here where the files actually exist.

Restored with the sync work from the 2026-08-20 run already in place: the
--abort flag, the corrected yt-dlp install advice, and the measurements behind
both.

Note that main's history was rewritten to strip these paths, so the tooling's
own per-file history does not exist on this branch. It is preserved on gitea
as pre-rewrite-20260820 and pre-rewrite-tooling-20260820.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UXfdJu7QhSJLr47K7koTDF

package.json

@@ -12,7 +12,8 @@
     "clean": "rm -rf dist",
     "lint": "tsc --noEmit",
     "test": "vitest run",
-    "test:watch": "vitest"
+    "test:watch": "vitest",
+    "jd2": "tsx scripts/jd2-sync.ts"
   },
   "dependencies": {
     "@tailwindcss/vite": "^4.1.14",