refactor: rename nutriphi module to food (Essen)

Complete rename across the entire monorepo pre-launch:
- Module, routes, API, i18n, standalone landing app directories
- All code identifiers, display names, logo component
- German user-facing label: "Essen" (English brand stays "Food")
- Dexie table nutriFavorites -> foodFavorites
- Infra configs (docker-compose, cloudflared, nginx, wrangler)

Zero residue of nutriphi remains. No data migration needed (pre-launch).

Follow-up: run pnpm install, update Cloudflare DNS
(food.mana.how), rename Cloudflare Pages project.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docker/nginx/landings.conf

@@ -80,11 +80,11 @@ server {
     include /etc/nginx/snippets/landing-common.conf;
 }
 
-# nutriphi.mana.how — NutriPhi Landing
+# food.mana.how — Food Landing
 server {
     listen 80;
-    server_name nutriphi.mana.how;
-    root /srv/landings/nutriphi;
+    server_name food.mana.how;
+    root /srv/landings/food;
     index index.html;
     include /etc/nginx/snippets/landing-common.conf;
 }