feat: SPA routing, projects/resume sections, deployment infra

- Add client-side router with History API pushState (router.ts, pages.ts)
- Extend overlay with projects grid/category/detail views and resume section
- Add Gitea CI/CD workflow and webhook deployment server
- Improve Docker Compose with nginx reverse proxy config
- Add deployment script and .env.example

.env.example

@@ -0,0 +1,13 @@
+# Environment variables for the webhook server
+# Copy this to .env and fill in the secret:
+#   cp .env.example .env
+
+# Gitea webhook secret — generate with:  openssl rand -hex 32
+WEBHOOK_SECRET=
+
+# Path to the repo containing docker-compose.yml
+REPO_DIR=/home/djoser/webgpu-portfolio
+
+# Bind address and port for the webhook listener
+LISTEN_HOST=0.0.0.0
+LISTEN_PORT=9000