feat(theme): animate public background with aurora and particles, polish landing pages

Add background_effect (aurora/particles), background_overlay tint and
opacity to the theme manager, rendered site-wide by ThemeVars on every
public page. Polish the home and register pages (hero mascot, live stat
pulse, date pills, photo strip, CTA band, theme-aware register intro,
i18n for home/register section).

src/messages/en.json

@@ -288,7 +288,11 @@
 			"sectionStatsLabel": "Live stats",
 			"sectionStatsTitle": "A community that keeps growing",
 			"sectionCommunityLabel": "Community",
-			"sectionCommunityTitle": "Make yourself at home"
+			"sectionCommunityTitle": "Make yourself at home",
+			"joinCtaTitle": "Ready to make yourself at home?",
+			"joinCtaBody": "Create your avatar, grab some furni and meet new friends — your hotel adventure starts here.",
+			"ctaJoin": "Join the hotel",
+			"browseCommunity": "Browse the community"
 		},
 		"news": {
 			"title": "News",
@@ -997,6 +1001,7 @@
 			"alreadyHaveAccountLink": "Sign in",
 			"register": "Register",
 			"whoIsOnline": "Who's online",
+			"newestCitizens": "Newest citizens",
 			"usersOnline": "{count} online",
 			"termsError": "You must accept the terms & rules to register.",
 			"usernameError": "Username is required.",
@@ -4810,6 +4815,15 @@
 							"applyBackground": "Apply background",
 							"uploadButton": "Upload image…",
 							"clearBackground": "Remove background",
+							"backgroundEffectLabel": "Effect",
+							"backgroundEffectHint": "Animate the public background with a gentle, theme-matched layer (aurora uses your primary/accent colors).",
+							"backgroundEffect_none": "None (plain background)",
+							"backgroundEffect_aurora": "Aurora glow",
+							"backgroundEffect_particles": "Floating particles",
+							"backgroundEffect_aurora-particles": "Aurora + particles",
+							"backgroundEffectPreview": "Effect: {effect} — shown behind the public site.",
+							"backgroundOverlayLabel": "Overlay tint",
+							"backgroundOverlayOpacityLabel": "Overlay strength",
 							"notice": {
 								"saved": "Theme saved.",
 								"applied": "Theme applied.",