fix: Docker build and runtime fixes

- Fix duplicate 'signature' variable in webhooks.ts
- Add Prisma binary target for Alpine Linux
- Fix tsconfig path alias (@/* -> ./src/*)
- Add missing next-themes dependency
- Add build args for NEXT_PUBLIC_* env vars
- Fix SSR issues with zustand and providers
- Add providers-wrapper with dynamic ssr:false import
- Add SSL certs and public dir for nginx
- Update Dockerfiles for proper Prisma engine handling

backend/Dockerfile

@@ -36,9 +36,12 @@ RUN npm install --legacy-peer-deps --omit=dev
 
 # Copy built files from builder
 COPY --from=builder /app/backend/dist ./backend/dist
-COPY --from=builder /app/backend/node_modules/.prisma ./backend/node_modules/.prisma
+COPY --from=builder /app/node_modules ./node_modules
 COPY --from=builder /app/backend/prisma ./backend/prisma
 
+# Ensure correct Prisma engine is available
+RUN ls -la /app/node_modules/.prisma/client/ | grep engine
+
 WORKDIR /app/backend
 
 # Expose port