Fix: update Dockerfile ENV syntax to key=value

Dockerfile

@@ -19,7 +19,7 @@ COPY . .
 
 # Environment variables must be present at build time for Next.js
 # Coolify will provide these, but we can set defaults
-ENV NEXT_TELEMETRY_DISABLED 1
+ENV NEXT_TELEMETRY_DISABLED=1
 
 RUN npm run build
 
@@ -27,8 +27,8 @@ RUN npm run build
 FROM base AS runner
 WORKDIR /app
 
-ENV NODE_ENV production
-ENV NEXT_TELEMETRY_DISABLED 1
+ENV NODE_ENV=production
+ENV NEXT_TELEMETRY_DISABLED=1
 
 RUN addgroup --system --gid 1001 nodejs
 RUN adduser --system --uid 1001 nextjs
@@ -48,8 +48,8 @@ USER nextjs
 
 EXPOSE 3000
 
-ENV PORT 3000
+ENV PORT=3000
 # set hostname to localhost
-ENV HOSTNAME "0.0.0.0"
+ENV HOSTNAME="0.0.0.0"
 
 CMD ["node", "server.js"]