fix: photo thumbnails always used localhost:9000 in production

getPublicUrl() runs in the browser (called from client components rendering
recipe thumbnails), but read the plain STORAGE_PUBLIC_URL env var — never
inlined into the client bundle, so every browser fell back to the hardcoded
localhost:9000 default regardless of the real deployed storage domain,
tripping CSP img-src and mixed-content blocks in production. Added a
NEXT_PUBLIC_STORAGE_PUBLIC_URL build arg (Dockerfile, compose.prod.yml) wired
from the same STORAGE_PUBLIC_URL value, and getPublicUrl() now reads that.

Verified locally: building with a fake public storage domain set shows it
correctly inlined into the client JS chunk (previously only the localhost
fallback ever appeared there).

compose.prod.yml

@@ -85,6 +85,7 @@ services:
         NEXT_PUBLIC_DISCORD_ENABLED: ${NEXT_PUBLIC_DISCORD_ENABLED}
         NEXT_PUBLIC_AUTHENTIK_ENABLED: ${NEXT_PUBLIC_AUTHENTIK_ENABLED}
         STORAGE_PUBLIC_URL: ${STORAGE_PUBLIC_URL}
+        NEXT_PUBLIC_STORAGE_PUBLIC_URL: ${STORAGE_PUBLIC_URL}
     restart: always
     environment:
       DATABASE_URL: postgresql://${POSTGRES_USER}:${POSTGRES_PASSWORD}@postgres:5432/${POSTGRES_DB}