chore: extract arcade into standalone repo

Arcade lives as its own pnpm workspace at ~/Documents/Code/arcade
now, with no @mana/* coupling. This drops every reference and the
games/ directory from the monorepo.

Removes:
- games/ directory (89 files: web + server + 22 HTML games + screenshots)
- @arcade/web, @arcade/server pnpm workspace entries (games/* globs)
- arcade scripts in root package.json (4 scripts)
- arcade.mana.how from mana-auth trusted origins + CORS_ORIGINS
- arcade entries in mana-apps registry, app-icons, URL overrides
- arcade.mana.how from cloudflared tunnel + prometheus blackbox probes
- arcade-web service block in docker-compose.macmini.yml
- generate-env.mjs entries for arcade server + web
- BRANDING_ONLY 'arcade' entry in registry consistency spec
- dead arcade translation keys in GuestWelcomeModal (DE+EN)
- arcade mention in CLAUDE.md, authentication guideline, MODULE_REGISTRY

Verified:
- services/mana-auth/src/auth/sso-config.spec.ts: 8/8 pass
- pnpm install regenerates lockfile cleanly (-536 lines)
- no remaining 'arcade' refs outside historical snapshot docs

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/shared-auth-ui/src/components/GuestWelcomeModal.svelte

@@ -64,7 +64,6 @@
 		inventory: ['Alles im Überblick behalten', 'Quelloffen & unabhängig', 'Privat by Design'],
 		uload: ['Links kürzen & verwalten', 'Quelloffen & unabhängig', 'Privat by Design'],
 		news: ['Nachrichten, kuratiert für dich', 'Quelloffen & unabhängig', 'Privat by Design'],
-		arcade: ['Spiele direkt im Browser', 'Quelloffen & unabhängig', 'Privat by Design'],
 		skilltree: ['Dein Fortschritt, sichtbar', 'Quelloffen & unabhängig', 'Privat by Design'],
 		food: ['Ernährung bewusst leben', 'Quelloffen & unabhängig', 'Privat by Design'],
 		wisekeep: ['Wissen bewahren & teilen', 'Quelloffen & unabhängig', 'Privat by Design'],
@@ -97,7 +96,6 @@
 		inventory: ['Keep track of everything', 'Open-source & independent', 'Private by design'],
 		uload: ['Shorten & manage links', 'Open-source & independent', 'Private by design'],
 		news: ['News, curated for you', 'Open-source & independent', 'Private by design'],
-		arcade: ['Games right in your browser', 'Open-source & independent', 'Private by design'],
 		skilltree: ['Your progress, visualized', 'Open-source & independent', 'Private by design'],
 		food: ['Mindful nutrition tracking', 'Open-source & independent', 'Private by design'],
 		wisekeep: ['Preserve & share knowledge', 'Open-source & independent', 'Private by design'],

packages/shared-branding/src/app-icons.ts

@@ -176,9 +176,6 @@ export const APP_ICONS = {
 	places: svgToDataUrl(
 		`<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><defs><linearGradient id="plc" x1="0%" y1="0%" x2="100%" y2="100%"><stop offset="0%" style="stop-color:#0ea5e9"/><stop offset="100%" style="stop-color:#0284c7"/></linearGradient></defs><rect width="100" height="100" rx="22" fill="url(#plc)"/><path d="M50 20c-14 0-25 11-25 25 0 20 25 38 25 38s25-18 25-38c0-14-11-25-25-25zm0 34a9 9 0 1 1 0-18 9 9 0 0 1 0 18z" fill="white"/></svg>`
 	),
-	arcade: svgToDataUrl(
-		`<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><defs><linearGradient id="ar" x1="0%" y1="0%" x2="100%" y2="100%"><stop offset="0%" style="stop-color:#ef4444"/><stop offset="100%" style="stop-color:#dc2626"/></linearGradient></defs><rect width="100" height="100" rx="22" fill="url(#ar)"/><rect x="25" y="30" width="50" height="35" rx="5" stroke="white" stroke-width="4" fill="none"/><path d="M38 65v10M62 65v10M32 75h36" stroke="white" stroke-width="4" stroke-linecap="round"/><circle cx="60" cy="44" r="4" fill="white"/><circle cx="68" cy="50" r="3" fill="white" fill-opacity="0.7"/><path d="M35 44h10M40 39v10" stroke="white" stroke-width="3" stroke-linecap="round"/></svg>`
-	),
 	events: svgToDataUrl(
 		`<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><defs><linearGradient id="ev" x1="0%" y1="0%" x2="100%" y2="100%"><stop offset="0%" style="stop-color:#f43f5e"/><stop offset="100%" style="stop-color:#be123c"/></linearGradient></defs><rect width="100" height="100" rx="22" fill="url(#ev)"/><path d="M22 78l14-44 30 30-44 14z" fill="white"/><path d="M36 34c4-6 12-8 18-4M50 22c4-2 10 0 12 6M62 28c6-2 12 2 12 10" stroke="white" stroke-width="3" stroke-linecap="round" fill="none"/><circle cx="74" cy="46" r="2.5" fill="white"/><circle cx="80" cy="58" r="2" fill="white" fill-opacity="0.8"/><circle cx="68" cy="62" r="2" fill="white" fill-opacity="0.7"/></svg>`
 	),

packages/shared-branding/src/mana-apps.ts

@@ -835,23 +835,6 @@ export const MANA_APPS: ManaApp[] = [
 		status: 'development',
 		requiredTier: 'guest',
 	},
-	{
-		id: 'arcade',
-		name: 'Arcade',
-		description: {
-			de: 'KI Browser-Spiele',
-			en: 'AI Browser Games',
-		},
-		longDescription: {
-			de: 'Sammlung von KI-generierten Browser-Spielen zum sofortigen Spielen.',
-			en: 'Collection of AI-generated browser games to play instantly.',
-		},
-		icon: APP_ICONS.arcade,
-		color: '#ef4444',
-		comingSoon: false,
-		status: 'beta',
-		requiredTier: 'guest',
-	},
 	{
 		id: 'drink',
 		name: 'Drink',
@@ -1312,8 +1295,6 @@ export const APP_SLIDER_LABELS = {
 const APP_URL_OVERRIDES: Partial<Record<AppIconId, { dev: string; prod: string }>> = {
 	// The unified app itself lives at the root, not at /mana.
 	mana: { dev: 'http://localhost:5173', prod: 'https://mana.how' },
-	// Standalone apps on their own subdomain / port.
-	arcade: { dev: 'http://localhost:5201', prod: 'https://arcade.mana.how' },
 };
 
 export const APP_URLS: Record<AppIconId, { dev: string; prod: string }> = Object.fromEntries(