feat: api key authentication (#291)

Co-authored-by: Elias Schneider <login@eliasschneider.com>

backend/internal/model/api_key.go

@@ -0,0 +1,18 @@
+package model
+
+import (
+	"github.com/pocket-id/pocket-id/backend/internal/model/types"
+)
+
+type ApiKey struct {
+	Base
+
+	Name        string `sortable:"true"`
+	Key         string
+	Description *string
+	ExpiresAt   datatype.DateTime  `sortable:"true"`
+	LastUsedAt  *datatype.DateTime `sortable:"true"`
+
+	UserID string
+	User   User
+}