feat: Add Swagger documentation for admin and master API endpoints

- Added Swagger documentation for the following admin endpoints:
  - Create a new master tenant
  - Create a new provider
  - Register a new model
  - List all models
  - Update a model
  - Force sync snapshot
  - Ingest logs

- Added Swagger documentation for the master endpoint:
  - Issue a child key

- Updated go.mod and go.sum to include necessary dependencies for Swagger.

internal/api/admin_handler.go

@@ -23,6 +23,18 @@ type CreateMasterRequest struct {
 	GlobalQPS    int    `json:"global_qps"`
 }
 
+// CreateMaster godoc
+// @Summary      Create a new master tenant
+// @Description  Create a new master account (tenant)
+// @Tags         admin
+// @Accept       json
+// @Produce      json
+// @Security     AdminAuth
+// @Param        master  body      CreateMasterRequest  true  "Master Info"
+// @Success      201     {object}  gin.H
+// @Failure      400     {object}  gin.H
+// @Failure      500     {object}  gin.H
+// @Router       /admin/masters [post]
 func (h *AdminHandler) CreateMaster(c *gin.Context) {
 	var req CreateMasterRequest
 	if err := c.ShouldBindJSON(&req); err != nil {