feat(server): implement structured logging, metrics, and dockerignore

- Configure structured logging via environment variable
- Add Prometheus metrics for HTTP request tracking and health
- Secure /metrics endpoint with IP allowlisting
- Update .dockerignore to exclude build artifacts

.dockerignore

@@ -8,3 +8,16 @@ build/
 .env
 *.log
 .git/
+dashboard/src/
+dashboard/static/
+dashboard/node_modules/
+dashboard/.svelte-kit/
+dashboard/package*.json
+dashboard/svelte.config.*
+dashboard/vite.config.*
+dashboard/tsconfig.*
+docs/
+scripts/
+*.md
+*.sql
+*.service