chore(deploy): add Dockerfile and nginx config for Coolify SPA hosting

Multi-stage build: node:22-alpine + pnpm builds, nginx:1.27-alpine
serves. VITE_* env vars are passed as build args because Vite inlines
them into the JS bundle at build time. nginx config does SPA fallback,
caches /assets/* immutably, and forces no-store on sw.js/index.html so
PWA updates propagate.

.dockerignore

@@ -0,0 +1,14 @@
+.git
+.gitignore
+node_modules
+dist
+.DS_Store
+.env
+.env.*
+!.env.example
+.vscode
+.idea
+*.log
+README.md
+src-legacy
+tests/examples