add initial project structure with configuration, models, and API key authentication

internal/models/rate_limit_hwid.go

@@ -0,0 +1,9 @@
+package models
+
+import "time"
+
+type RateLimitHWID struct {
+	HWID        string    `db:"hwid"       json:"hwid"`
+	Requests    int       `db:"requests"   json:"requests"`
+	WindowStart time.Time `db:"window_start" json:"window_start"`
+}