feat: add Docker deployment, UAT test suites, and fix signup middleware bug

- Add Dockerfile, docker-entrypoint.sh, and .dockerignore for containerized deployment
- Fix middleware to exclude /api/tenants/signup from auth (P0 signup bug)
- Add Playwright E2E tests (16 browser tests) and curl-based API test script (80 tests)
- Add playwright config and dev dependency
- Update .gitignore with proper exclusions
- Add v1 milestone audit report and ISP system PRD

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

Dockerfile

@@ -9,6 +9,12 @@ RUN npm ci
 # Copy source code
 COPY . .
 
+# Generate Prisma client at build time
+RUN npx prisma generate
+
+# Make entrypoint executable
+RUN chmod +x docker-entrypoint.sh
+
 EXPOSE 3000
 
-CMD ["npm", "run", "dev"]
+ENTRYPOINT ["./docker-entrypoint.sh"]