Fix CUDA-graph replay race + many_faces enhancer regression

Two issues surfaced in post-squash review of f65aeae:

1. CUDA-graph replay buffers were shared across threads with no lock.
   `_cuda_graph_swap_inference` mutates module-level ort_input/ort_latent
   and runs run_with_iobinding — concurrent swap calls on Windows/CUDA
   could overwrite each other's bound input buffers before replay,
   producing wrong-face output. Added `_cuda_graph_lock` around the
   full update/run/read sequence.

2. Face enhancer loop unconditionally broke after the first face, so
   `many_faces=True` silently enhanced only one face. Also, the
   single-slot temporal cache would paste the same enhancement onto
   every target if reused in many-faces mode. Gated the break on
   `not many_faces_mode` and disabled the cache path in that mode.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

modules/processors/frame/face_enhancer.py

@@ -311,7 +311,11 @@ def enhance_face(temp_frame: Frame, detected_faces=None) -> Frame:
         return temp_frame
 
     # Temporal caching: only available when faces are pre-detected (live mode)
-    use_cache = detected_faces is not None
+    # AND we're in single-face mode — the cache holds exactly one enhancement,
+    # so reusing it in many_faces mode would paste the same face onto every
+    # detected target.
+    many_faces_mode = getattr(modules.globals, "many_faces", False)
+    use_cache = detected_faces is not None and not many_faces_mode
     if use_cache:
         _enh_live_cache['frame_count'] += 1
         run_inference_this_frame = (_enh_live_cache['frame_count'] % _ENH_INTERVAL == 0
@@ -372,7 +376,8 @@ def enhance_face(temp_frame: Frame, detected_faces=None) -> Frame:
                     cached['affine_matrix'],
                     output_size=cached['align_size'],
                 )
-        break  # single-face live mode — only process first face
+        if not many_faces_mode:
+            break  # single-face live mode — only process first face
 
     return temp_frame