NEWS RELAUNCH CUTOVER: promote the hub to /, feed to /news, go public

The big flip. /home3 (hub) becomes /; the feed lives at /news; both indexable.
- PROMOTE: routes/+page.svelte is now the hub (was the interim NewsFeed wrapper);
  noindex removed; "Read more good news" → /news. routes/home3 + home2 deleted.
- routes/+page.js: redirects legacy root-query links (/?view=latest, /?tag, /?source,
  /?q, /?view=today→highlights) to /news before the hub renders (no flash).
- /news: noindex dropped (route meta + Caddy @newsHidden removed); now public.
- LINKS: HubBar brand/Home → /, News default → /news; HubShell/art/play back → /;
  account Following + share.py Explore/Browse/source → /news.
- FOOTER: one shared Footer.svelte (motto + Send feedback + slot) across Hub/News/
  Play/Art/HubShell/Account/Zen; global layout footer removed (FeedbackModal stays).
- SITEMAP: + /news /art /play /word /quote /onthisday; cap 5k→50k; gated on
  has-summary; paywalled excluded; HEAD now 200 (api_route GET+HEAD).
- Head-patcher: /news entry. PWA + shell description broadened to the hub.
- Caddy: @newsHidden dropped; @hidden now admin-only (word/quote/onthisday public);
  /home2,/home3 → / 301. Mirrored to deploy/caddy snapshot.

425 backend + 36 frontend tests green; build clean; Caddy valid.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/static/manifest.webmanifest

@@ -1,7 +1,7 @@
 {
   "name": "Upbeat Bytes",
   "short_name": "Upbeat Bytes",
-  "description": "Calm, constructive news worth your attention — and nothing that isn't.",
+  "description": "A calmer, brighter corner of the internet: good news, daily art, small games, and little resets.",
   "start_url": "/",
   "scope": "/",
   "display": "standalone",