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>

deploy/caddy/Caddyfile.snapshot

@@ -46,6 +46,12 @@ upbeatbytes.com {
 	encode gzip zstd
 
 	# Retired prototype routes (promoted/removed at the news relaunch) → the hub.
+	@oldhome path /home2 /home2.html /home3 /home3.html
+	handle @oldhome {
+		redir / permanent
+	}
+
+	# Dynamic API + server-rendered pages (share, digest, sitemap) → FastAPI.
 	@api path /api/* /healthz /docs /docs/* /openapi.json /a/* /today /sitemap.xml
 	handle @api {
 		reverse_proxy upbeatbytes-api:8000
@@ -60,15 +66,10 @@ upbeatbytes.com {
 		# Hidden in-progress prototypes — keep crawlers out at the HTTP level (the JS
 		# <meta robots> isn't seen by non-JS bots since the static shell is generic).
 		# Only admin stays out of the index now — news, art, play, and the joy pages are public.
-		header @hidden X-Robots-Tag "noindex, nofollow"
+		@hidden path /admin /admin.html
+		header @hidden X-Robots-Tag "noindex, nofollow"
 
 		# Content-hashed assets never change for a given URL — cache them forever.
-		# noindex (FOLLOW, so link equity still flows) until cutover, when this line is removed
-		# and /news enters the sitemap. Avoids publishing a duplicate indexable feed.
-		@newsHidden path /news /news.html
-		header @newsHidden X-Robots-Tag "noindex, follow"
-
-		# Content-hashed assets never change for a given URL — cache them forever.
 		@immutable path /_app/immutable/*
 		header @immutable Cache-Control "public, max-age=31536000, immutable"