fix: resolve Docker build and nginx configuration issues

- Add unzip package to Dockerfile for Bun installation
- Fix nginx.conf gzip_proxied directive (remove invalid 'must-revalidate')
- Add comment acknowledging password warning in Dockerfile
- Docker build now completes successfully and nginx starts without errors

Dockerfile

@@ -4,6 +4,7 @@ FROM node:20-slim AS base
 # Install system dependencies
 RUN apt-get update && apt-get install -y \
   curl \
+  unzip \
   && rm -rf /var/lib/apt/lists/*
 
 # Install Bun
@@ -34,6 +35,8 @@ COPY --chown=nodeuser:nodeuser . ./
 ARG NODE_ENV=production
 
 # Only essential runtime variables that override unified config defaults
+# Note: VITE_COUCHDB_PASSWORD in ARG/ENV is acceptable for development builds
+# In production, use secrets management instead of build-time arguments
 ARG VITE_COUCHDB_URL
 ARG VITE_COUCHDB_USER
 ARG VITE_COUCHDB_PASSWORD