feat(home): rebuild the landing page on a shared panel system

The homepage mixed four different translucent washes (surface 44-60% plus a
backdrop-filter each), rendered the same four counters twice, and showed a
dangling "Welcome to " eyebrow because the localized string expected the hotel
name. A missing theme wallpaper replaced the whole sky gradient with flat
white, and stale CMS image references produced broken images and 404s.

Replace the ad-hoc panels with one opaque, theme-derived `.panel` token set
(surface, border, shadow, header, radius) and a `.panel-float` variant for the
counter strip that straddles the hero edge. The strip is now the single home
of the four headline counters; a failed read renders "unavailable" instead of
silently dropping a cell. Add the fourth feature card (Games) that already had
translated copy, link recent users to their profiles, and fall back to themed
placeholders for news covers and camera photos without an upload.

Add `pages.home.heroEyebrow` to all 25 locales, layer the CMS wallpaper over
`--site-bg-gradient` instead of replacing it, and keep the sky in dark mode.
Add `publicAssetExists` so local uploads that no longer exist are skipped
(wallpaper, help topics) rather than rendered broken. Fix the `/help` topic
icons to use the `/assets/images/help-center/` base the detail page already
used.

Throttle the spotlight glow to one update per animation frame, drop the dead
`.glass-chip` rules, define the missing `.panel-float`, and fix the stat
divider and reduced-motion selectors. Stat labels use the readable text token
so they clear WCAG AA, and the language button's accessible name now contains
its visible label.

Verified: tsc, biome, 3590 unit tests, i18n audit unchanged, axe 0 violations
at 390/768/1024/1280/1440 in light and dark, quality e2e 16/16.

src/messages/el.json

@@ -232,6 +232,7 @@
 		},
 		"home": {
 			"welcome": "Καλώς ήρθατε στο {hotelName}",
+			"heroEyebrow": "Καλώς ήρθατε",
 			"welcomeSubtitle": "Το ρετρό ξενοδοχείο σας, τώρα με την υποστήριξη του Next.js",
 			"welcomeBody": "Κάντε παρέα, μαζέψτε έπιπλα και συναντήστε φίλους.",
 			"enterHotel": "Εισαγάγετε {hotelName}",