feat: add registry config, image upload/download, and OCI format support

Backend:
- Add registry_address configuration API (GET/POST)
- Add tar image upload with OCI and Docker format support
- Add image download with streaming optimization
- Fix blob download using c.Send (Fiber v3 SendStream bug)
- Add registry_address prefix stripping for all OCI v2 endpoints
- Add AGENTS.md for project documentation

Frontend:
- Add settings store with Snackbar notifications
- Add image upload dialog with progress bar
- Add download state tracking with multi-stage feedback
- Replace alert() with MUI Snackbar messages
- Display image names without registry_address prefix

🤖 Generated with [Qoder](https://qoder.com)

internal/model/model.go

@@ -68,3 +68,14 @@ type BlobUpload struct {
 	Path       string `gorm:"not null" json:"path"`                   // ??????
 	Size       int64  `gorm:"default:0" json:"size"`                  // ?????
 }
+
+// RegistryConfig registry ?????
+type RegistryConfig struct {
+	ID        uint           `gorm:"primarykey" json:"id"`
+	CreatedAt time.Time      `json:"created_at"`
+	UpdatedAt time.Time      `json:"updated_at"`
+	DeletedAt gorm.DeletedAt `gorm:"index" json:"-"`
+
+	Key   string `gorm:"uniqueIndex;not null" json:"key"`   // ???? key
+	Value string `gorm:"type:text" json:"value"`            // ???? value
+}