feat: add system dashboard (Go monitoring app)

Migrated from a sepharyana-hub/infra/dashboard.
- Docker container monitor via socket
- Jaeger trace viewer + Prometheus metrics
- SVG charts (donut, line, gauge)
- Proxies to Jaeger/Prometheus APIs

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

dashboard/go.mod

@@ -0,0 +1,3 @@
+module github.com/asepharyana/asepharyana-hub-hub/dashboard
+
+go 1.24