fix: improve URL path handling in local storage for special characters (#4378)

* refactor: improve URL path handling in local storage system

Enhanced the local storage implementation to properly handle URL-decoded paths
and fix issues with file paths containing special characters. Added decodedPath
field to localStorage struct to separate URL parsing concerns from file system
operations.

Key changes:
- Added decodedPath field to localStorage struct for proper URL decoding
- Modified newLocalStorage to use decoded path instead of modifying original URL
- Fixed Windows path handling to work with decoded paths
- Improved URL escaping in storage.For() to handle special characters
- Added comprehensive test suite covering URL decoding, symlink resolution,
  Windows paths, and edge cases
- Refactored test extractor to use mockTestExtractor for better isolation

This ensures that file paths with spaces, hash symbols, and other special
characters are handled correctly throughout the storage system.

Signed-off-by: Deluan <deluan@navidrome.org>

* fix(tests): fix test file permissions and add missing tests.Init call

* refactor(tests): remove redundant test

Signed-off-by: Deluan <deluan@navidrome.org>

* fix: URL building for Windows and remove redundant variable

Signed-off-by: Deluan <deluan@navidrome.org>

* refactor: simplify URL path escaping in local storage

Signed-off-by: Deluan <deluan@navidrome.org>

---------

Signed-off-by: Deluan <deluan@navidrome.org>

core/storage/storage.go

@@ -6,6 +6,8 @@ import (
 	"path/filepath"
 	"strings"
 	"sync"
+
+	"github.com/navidrome/navidrome/utils/slice"
 )
 
 const LocalSchemaID = "file"
@@ -36,7 +38,14 @@ func For(uri string) (Storage, error) {
 	if len(parts) < 2 {
 		uri, _ = filepath.Abs(uri)
 		uri = filepath.ToSlash(uri)
-		uri = LocalSchemaID + "://" + uri
+
+		// Properly escape each path component using URL standards
+		pathParts := strings.Split(uri, "/")
+		escapedParts := slice.Map(pathParts, func(s string) string {
+			return url.PathEscape(s)
+		})
+
+		uri = LocalSchemaID + "://" + strings.Join(escapedParts, "/")
 	}
 
 	u, err := url.Parse(uri)