feat: Initial OPHION structure

- Go backend with Fiber framework
- Agent for metrics collection
- Docker Compose for self-hosted
- Auth middleware (JWT + API Keys)
- Rate limiting
- Install script

go.mod

@@ -0,0 +1,9 @@
+module github.com/bigtux/ophion
+
+go 1.22
+
+require (
+	github.com/gofiber/fiber/v2 v2.52.0
+	github.com/shirou/gopsutil/v3 v3.24.1
+	github.com/golang-jwt/jwt/v5 v5.2.0
+)