fix(utils): URL-encode media paths to handle special characters in filenames

Cover image URLs with special characters like parentheses, #, ?, or
spaces would break because browsers interpret them as URL delimiters.
Apply url.PathEscape() per path segment in ResolveMediaURL so the
server can correctly resolve files like "Wonder Woman (2016) #001.cbz.cover.jpg".

Also adds a package doc comment and fixes the exported function comment.

internal/utils/mediaurl.go

@@ -1,7 +1,9 @@
+// Package utils provides helper functions for URL resolution, ISBN handling, and tag management.
 package utils
 
 import (
 	"fmt"
+	"net/url"
 	"path/filepath"
 	"strings"
 
@@ -9,7 +11,7 @@ import (
 	"github.com/jackc/pgx/v5/pgtype"
 )
 
-// resolveMediaURL resolves a relative path (cover or file) to a full URL
+// ResolveMediaURL resolves a relative path (cover or file) to a full URL
 func ResolveMediaURL(libraryID pgtype.UUID, relativePath pgtype.Text) string {
 	if !relativePath.Valid || relativePath.String == "" {
 		return ""
@@ -24,5 +26,10 @@ func ResolveMediaURL(libraryID pgtype.UUID, relativePath pgtype.Text) string {
 	}
 
 	libraryIDStr := uuid.UUID(libraryID.Bytes).String()
-	return fmt.Sprintf("/uploads/library-%s/%s", libraryIDStr, relativePath.String)
+	segments := strings.Split(relativePath.String, "/")
+	for i, seg := range segments {
+		segments[i] = url.PathEscape(seg)
+	}
+	encodedPath := strings.Join(segments, "/")
+	return fmt.Sprintf("/uploads/library-%s/%s", libraryIDStr, encodedPath)
 }