Correctly place built frontend files in the server directory

Update Dockerfile to copy the built frontend assets to `/app/server/public`, resolving the "Could not find the build directory" error.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: ceced2fc-aa46-458d-ba87-ddd4b7bb1518
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/659922a9-0087-461c-90dd-6d9a58b81d4d/ceced2fc-aa46-458d-ba87-ddd4b7bb1518/mgDhgbG

Dockerfile

@@ -23,9 +23,6 @@ FROM base AS production
 # Install ALL dependencies (including tsx for running TypeScript in production)
 COPY --from=dependencies /app/node_modules ./node_modules
 
-# Copy built frontend
-COPY --from=build /app/dist/public ./dist/public
-
 # Copy server source files (TypeScript)
 COPY --from=build /app/server ./server
 COPY --from=build /app/shared ./shared
@@ -33,6 +30,9 @@ COPY --from=build /app/drizzle.config.ts ./
 COPY --from=build /app/package.json ./
 COPY --from=build /app/tsconfig.json ./
 
+# Copy built frontend to the location static.ts expects
+COPY --from=build /app/dist/public ./server/public
+
 # Set environment variables
 ENV NODE_ENV=production
 ENV PORT=5000