Fase 0: scaffold monorepo, SvelteKit skeleton, and dev infrastructure

- Turborepo + pnpm workspaces with apps/web and packages/types
- SvelteKit app: Tailwind, Paraglide i18n (en/es), keycloak-js, Supabase client,
  auth/collective stores, PWA service worker skeleton, all route placeholders
- packages/types: domain types (User, Collective, ShoppingList, etc.) and
  database.ts placeholder for generated types
- Justfile with dev, db-*, kc-*, build, backup, restore, deploy recipes
- infra/docker-compose.dev.yml: Postgres 15, GoTrue, PostgREST, Realtime v2.83,
  Storage, Kong (port 8001), Studio, Keycloak 24
- infra/docker-compose.prod.yml, kong.yml, db-init scripts, backup/deploy scripts
- keycloak/realm-export.json with colectivo realm and 5 dev test users
- supabase/config.toml and seed.sql with sample collective and items
- GitHub Actions: ci.yml (lint+typecheck+build) and deploy.yml (GHCR + SSH)
- .env.example documenting all required variables
- Fixed docker-compose issues: Studio image tag, Kong port conflict (8001),
  internal role passwords init script, Realtime METRICS_JWT_SECRET/APP_NAME

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/web/src/routes/onboarding/+page.svelte

@@ -0,0 +1,25 @@
+<script lang="ts">
+	import * as m from '$lib/paraglide/messages';
+</script>
+
+<div class="flex min-h-screen flex-col items-center justify-center bg-background p-6">
+	<div class="w-full max-w-sm space-y-6">
+		<div class="text-center">
+			<h1 class="text-2xl font-bold text-slate-900 dark:text-slate-50">{m.onboarding_title()}</h1>
+		</div>
+
+		<!-- Fase 1: collective creation / join form -->
+		<div class="space-y-3">
+			<button
+				class="w-full rounded-md bg-slate-900 px-4 py-3 text-sm font-medium text-white hover:bg-slate-700 dark:bg-slate-50 dark:text-slate-900 dark:hover:bg-slate-200"
+			>
+				{m.onboarding_create_collective()}
+			</button>
+			<button
+				class="w-full rounded-md border border-slate-200 bg-surface px-4 py-3 text-sm font-medium text-slate-700 hover:bg-slate-50 dark:border-slate-700 dark:text-slate-300 dark:hover:bg-slate-800"
+			>
+				{m.onboarding_join_collective()}
+			</button>
+		</div>
+	</div>
+</div>