fix: Resolve isinstance() TypeError and undefined variable errors

Fixed two critical bugs in NFO processing:

1. isinstance() TypeError: Fixed XML comment detection in update_episode_nfo_preserving_name
   - ET.Comment is not a proper type for isinstance()
   - Added safer comment detection using type checking and string matching

2. Undefined variable: Fixed episode_filename reference in create_episode_nfo
   - Variable only defined in fallback case but referenced in all cases
   - Changed to use nfo_path.name which is always available

These fixes resolve the errors preventing NFO file updates for existing
long-named NFO files.

VERSION

@@ -1 +1 @@
-1.9.4
+1.9.5

core/nfo_manager.py

@@ -685,7 +685,7 @@ class NFOManager:
                     if episode.tag != "episodedetails":
                         raise ValueError("Root element is not <episodedetails>")
                     
-                    print(f"📝 Updating standard NFO: {episode_filename}")
+                    print(f"📝 Updating existing NFO: {nfo_path.name}")
                     
                     # Remove existing NFOGuard fields to re-add them at the bottom
                     nfoguard_fields = ["aired", "dateadded", "season", "episode"]
@@ -970,8 +970,11 @@ class NFOManager:
                     episode.remove(existing_field)
             
             # Remove any existing NFOGuard comments
-            for child in episode:
+            for child in list(episode):
-                if isinstance(child, ET.Comment):
+                if hasattr(child, 'tag') and child.tag is ET.Comment:
+                    if self.manager_brand in str(child):
+                        episode.remove(child)
+                elif str(type(child)).find('Comment') != -1:
                     if self.manager_brand in str(child):
                         episode.remove(child)