Add landing page, Docker setup, and CI/CD pipeline

React + Vite + TypeScript + Tailwind frontend with landing page,
Docker Compose for dev and prod (nginx-proxy integration),
and Gitea Actions workflow for automated deployment.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/nginx.conf

@@ -0,0 +1,16 @@
+server {
+    listen 80;
+    root /usr/share/nginx/html;
+    index index.html;
+
+    # SPA fallback
+    location / {
+        try_files $uri $uri/ /index.html;
+    }
+
+    # Cache immutable assets
+    location /assets/ {
+        expires 1y;
+        add_header Cache-Control "public, immutable";
+    }
+}