feat: Update storage provider form and validation enhancements

- Added new HTML elements and JavaScript functionality to improve the user experience for WebDAV and Hetzner storage providers.
- Updated form field descriptions and placeholders for clarity, ensuring users understand the required input.
- Enhanced validation logic for WebDAV to ensure the host includes the protocol.
- Improved logging for debugging during form submissions, particularly for WebDAV credentials.
- Removed the deprecated provider form component to streamline the codebase.

internal/web/handlers/storage_provider_handlers.go

@@ -2,6 +2,7 @@ package handlers
 
 import (
 	"fmt"
+	"log"
 	"net/http"
 	"strconv"
 	"strings"
@@ -446,6 +447,19 @@ func (h *Handlers) parseProviderFromForm(c *gin.Context) (db.StorageProvider, er
 		provider.Username = c.PostForm("username")
 		provider.Password = c.PostForm("password")
 
+		// Log for debugging
+		log.Printf("WebDAV provider: username=%s, password present=%v",
+			provider.Username, provider.Password != "")
+
+		// WebDAV uses Host without port (full URL)
+		if provider.Host == "" {
+			return provider, fmt.Errorf("host/URL is required for WebDAV provider")
+		}
+
+		if provider.Username == "" {
+			return provider, fmt.Errorf("username is required for WebDAV provider")
+		}
+
 	case db.ProviderTypeS3, db.ProviderTypeWasabi, db.ProviderTypeMinio, db.ProviderTypeB2:
 		// S3 specific fields
 		provider.AccessKey = c.PostForm("accessKey")