fix: Use public Docker Hub images instead of private registry

Switch FROM directives to use public Docker Hub images:
- node:20-slim (instead of git.spdy.io/creationshop/node:20-slim)
- nginx:alpine (instead of git.spdy.io/creationshop/nginx:alpine)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

findagram/frontend/Dockerfile

@@ -1,5 +1,5 @@
 # Build stage
-FROM git.spdy.io/creationshop/node:20-slim AS builder
+FROM node:20-slim AS builder
 
 WORKDIR /app
 
@@ -25,7 +25,7 @@ COPY . .
 RUN npm run build
 
 # Production stage
-FROM git.spdy.io/creationshop/nginx:alpine
+FROM nginx:alpine
 
 # Copy built assets from builder stage (CRA outputs to /build)
 COPY --from=builder /app/build /usr/share/nginx/html