feat: public marketing site (vitrine)

Adds a (marketing) route group -- Home, Features, About, Privacy,
Terms, Contact -- reusing the app's design system/i18n/deploy
pipeline rather than a separate site. Root page.tsx now branches on
session instead of always redirecting to /recipes: logged-in visitors
still land in the app unchanged, logged-out visitors see the vitrine
home page.

The actual integration point: proxy.ts's PUBLIC_PATHS previously sent
every anonymous "/" request straight to /login before page.tsx's
redirect ever ran. Added the new marketing routes to PUBLIC_PATHS,
plus a separate exact-match list for "/" itself -- it can't go in the
startsWith-matched array, since every path starts with "/" and that
would make the whole app public.

Also adds app/sitemap.ts and app/robots.ts (neither existed before),
disallowing the authenticated app and the unlisted /r/ and /s/ share
routes from crawling while allowing /u/ public profiles.

Pricing page deliberately not included -- waiting on Stripe Checkout
(STRIPE_PLAN.md) so its CTA goes somewhere real. Privacy/Terms are
structural drafts flagged inline as not lawyer-reviewed, per
STRIPE_PLAN.md's own tax-advice caveat -- same spirit here.

Verified with a full production build (pnpm build) -- compiles clean,
all 7 new routes render, since there's no DB in this sandbox to run
the dev server against for a real click-through.

v0.48.0

apps/web/messages/en.json

@@ -1,4 +1,62 @@
 {
+  "marketing": {
+    "nav": {
+      "features": "Features",
+      "about": "About",
+      "openApp": "Open app",
+      "login": "Log in",
+      "signup": "Sign up"
+    },
+    "footer": {
+      "about": "About",
+      "privacy": "Privacy",
+      "terms": "Terms",
+      "contact": "Contact",
+      "copyright": "© {year} Epicure"
+    },
+    "home": {
+      "heroTitle": "Your AI-powered recipe book",
+      "heroSubtitle": "Generate, organize, and share recipes — plan meals, track your pantry, and cook with an assistant that can act on your behalf.",
+      "ctaPrimary": "Get started free",
+      "ctaSecondary": "See features",
+      "bottomCtaTitle": "Start cooking smarter",
+      "bottomCtaSubtitle": "Free to start. No credit card required.",
+      "highlights": {
+        "ai": { "title": "AI recipe generation", "description": "Generate a full recipe from an idea, a photo, or a URL — vision and text models work together to write the details." },
+        "assistant": { "title": "Cooking assistant", "description": "Ask cooking questions anytime — it can even draft a recipe or shopping list right in the conversation, for you to review and confirm." },
+        "mealPlan": { "title": "Meal planning", "description": "Plan your week, generate a plan with AI, and turn it straight into a shopping list." },
+        "pantry": { "title": "Pantry tracking", "description": "Know what you have on hand — scan it in, and let recipes account for it automatically." },
+        "social": { "title": "Share & discover", "description": "Follow other cooks, rate and comment on recipes, and control exactly who can see yours." },
+        "batchCook": { "title": "Batch cooking", "description": "Cook once, eat all week — dedicated batch-cook planning with fridge/freezer guidance." }
+      }
+    },
+    "features": {
+      "title": "Everything you need to cook smarter",
+      "subtitle": "From a single idea to a finished, organized recipe collection.",
+      "cta": "Try it free",
+      "items": {
+        "ai": { "title": "AI recipe generation", "description": "Generate a recipe from a short idea, a URL, or a description — dish or drink, automatically detected." },
+        "photoImport": { "title": "Import from a photo", "description": "A vision model recognizes what's in the photo, then a text model writes the full recipe from that description." },
+        "assistant": { "title": "Cooking assistant with tool-calling", "description": "A conversational assistant for cooking questions that can also draft a recipe or shopping-list additions for you to confirm — nothing saves without your say." },
+        "mealPlan": { "title": "AI meal planning", "description": "Generate a week of meals around your preferences, dietary needs, and what's already in your pantry." },
+        "pantry": { "title": "Pantry tracking", "description": "Track what you have — scan barcodes or photos — and let it inform meal planning and shopping lists." },
+        "shoppingList": { "title": "Shopping lists", "description": "Multiple lists, shared with others, auto-populated from recipes or meal plans." },
+        "social": { "title": "Follows, ratings & comments", "description": "A social layer for recipes — follow other cooks, rate and review, with granular visibility controls including followers-only." },
+        "batchCook": { "title": "Batch cooking", "description": "Plan cook-once-eat-all-week sessions with per-dish fridge/freezer guidance." }
+      }
+    },
+    "about": {
+      "title": "About Epicure",
+      "paragraphs": [
+        "Epicure started as a simple idea: a recipe book that actually keeps up with how you cook — planning, pantry, and AI all in one place instead of five different apps.",
+        "It's an independent project, built and maintained by one person, growing based on what's actually useful to the people using it."
+      ]
+    },
+    "contact": {
+      "title": "Get in touch",
+      "subtitle": "Questions, feedback, or something broken — email us and we'll get back to you."
+    }
+  },
   "nav": {
     "menu": "Menu",
     "recipes": "Recipes",