fix: bypass tsc -b in Docker build, use vite directly

tsc -b with project references fails in the Alpine Docker environment
(TypeScript 5.9 + no composite:true on referenced configs). Vite uses
esbuild for TS compilation anyway, so tsc -b only served as a type-check
which is redundant in a production build.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

flight-comparator/Dockerfile.frontend

@@ -5,7 +5,7 @@ WORKDIR /app
 COPY frontend/package*.json ./
 RUN npm ci
 COPY frontend/ .
-RUN npm run build
+RUN npx vite build
 
 # ── Stage 2: Serve with nginx ──────────────────────────────────────────────
 FROM nginx:alpine