Blender 5.0 compat + STB XML import + sequence/stamps improvements

- Fix Blender 5.0 API: active_sequence_strip → active_strip, bracket
  property access on AddonPreferences, _RestrictContext during register()
- Fix new_effect() frame_end → length for Blender 5.0
- Fix OTIO adapter kwargs (rate/ignore_timecode_mismatch only for cmx_3600)
- Fix OTIO global_start_time RationalTime → int conversion
- Add Import STB XML operator with movie strip import and XML patching
  for Storyboard Pro transitions missing <alignment>
- Add Create Sequence Strip operator (select shots → create sequence)
- Improve Set Stamps: channel at top, no conflict with existing strips,
  use raw strip names in templates
- TVSHOW episode fixes: sequence loading, episode creation
- Kitsu: new_asset, new_episode, admin_connect fix, gazu version pin
- Fix escape warnings in file_utils regex patterns
- Guard handler registration against duplicates

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scene_cut_detection.py

@@ -11,7 +11,7 @@ def detect_scene_change(strip, movie_type="ANIMATED", threshold=0.5, frame_start
     """Launch ffmpeg command to detect changing frames from a movie strip.
 
     Args:
-        movie_strip (bpy.types.Sequence): blender sequence strip to detect changes.
+        movie_strip (bpy.types.Strip): blender sequence strip to detect changes.
         threshold (float): value of the detection factor (from 0 to 1).
         frame_start (int, optional): first frame to detect.
             Defaults to None.