build(confidence-engine) fix dockerfile env var

Dockerfile

@@ -3,8 +3,11 @@ FROM node:22-alpine AS builder
 
 WORKDIR /app
 
-ENV NEXT_PUBLIC_SUPABASE_URL="" \
-    NEXT_PUBLIC_SUPABASE_ANON_KEY=""
+ARG NEXT_PUBLIC_SUPABASE_URL
+ARG NEXT_PUBLIC_SUPABASE_ANON_KEY
+
+ENV NEXT_PUBLIC_SUPABASE_URL=${NEXT_PUBLIC_SUPABASE_URL} \
+    NEXT_PUBLIC_SUPABASE_ANON_KEY=${NEXT_PUBLIC_SUPABASE_ANON_KEY}
 
 COPY package.json package-lock.json* yarn.lock* pnpm-lock.yaml* ./
 
@@ -20,9 +23,7 @@ RUN corepack enable && \
 
 COPY . .
 
-RUN NEXT_PUBLIC_SUPABASE_URL=${NEXT_PUBLIC_SUPABASE_URL} \
-    NEXT_PUBLIC_SUPABASE_ANON_KEY=${NEXT_PUBLIC_SUPABASE_ANON_KEY} \
-    next build
+RUN npm run build
 
 # ── Stage 2: Production runtime ────────────────────────────────────────
 FROM node:22-alpine AS runner