fix: README, .env.example, ErrorBoundary, client-logger, HEALTHCHECK, Docker hygiene

- README: version v0.2.6.8, corrected stale gate claim, updated changelog
- .env.example: merged two competing files into one, deleted bootstrap duplicate
- ErrorBoundary: new component wrapping app, prevents white-screen crashes
- Layout sidebar: version display from /api/health, Docs link to GitHub
- client-logger: debug/trace logger gated behind localStorage.redflag_debug=1,
  routes through existing /logs/client-error server endpoint (ETHOS #1)
- All web console.log calls rerouted through client-logger instead of deleted
- Server health endpoint returns version field
- Server accepts client_debug/client_trace in error_type validation
- Dockerfiles: pinned alpine:latest->3.21, nginx:alpine->1.27-alpine,
  added HEALTHCHECK directives
- docker-compose: healthcheck blocks for server and web services
- .dockerignore: created to slim Docker build context

web/Dockerfile

@@ -16,7 +16,10 @@ COPY . .
 RUN npx vite build
 
 # Production stage
-FROM nginx:alpine
+FROM nginx:1.27-alpine
+
+HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
+  CMD wget --no-verbose --tries=1 --spider http://localhost:80/ || exit 1
 
 # Copy built assets from build stage
 COPY --from=build /app/dist /usr/share/nginx/html