Fix image flash bug - remove 4 unnecessary yields

Removed yields that caused brief flashes of outdated images before
showing properly decoded results. This affected both standard and
artistic pipelines during first and second enhancement passes.

Removed yields:
- Standard line 1944: Black/white QR after first sampling
- Standard line 2031: First pass result after second sampling
- Artistic line 2369: Old QR after first sampling
- Artistic line 2464: First pass result after second sampling

Users now see smooth progression from animation frames directly to
final decoded images without intermediate flashes. Progress messages
still update via log_progress().

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

app.py

@@ -1938,10 +1938,10 @@ def _pipeline_standard(
                 latent_image=get_value_at_index(emptylatentimage_5, 0),
             )
 
-        # Yield progress update after first sampling completes
+        # Progress update after first sampling completes (no yield to avoid showing base QR)
         msg = "First pass sampling complete... decoding image"
         log_progress(msg, gr_progress, 0.4)
-        yield base_qr_pil, msg  # Yield with same image as before
+        # Removed yield here - caused flash of black/white QR before decoded image
 
         # Calculate optimal tile size for this image - disable for now
         # tile_size, overlap = calculate_vae_tile_size(image_size)
@@ -2025,10 +2025,10 @@ def _pipeline_standard(
                 latent_image=get_value_at_index(emptylatentimage_17, 0),
             )
 
-        # Yield progress update after second sampling completes
+        # Progress update after second sampling completes (no yield to avoid showing first pass)
         msg = "Second pass sampling complete... decoding final image"
         log_progress(msg, gr_progress, 0.8)
-        yield mid_pil, msg  # Yield with previous image
+        # Removed yield here - caused flash of first pass image before final decoded
 
         # Second pass is always 2x original, calculate based on doubled size
         tile_size_2x, overlap_2x = calculate_vae_tile_size(image_size * 2)
@@ -2363,10 +2363,10 @@ def _pipeline_artistic(
             latent_image=get_value_at_index(latent_image, 0),
         )
 
-    # Yield progress update after first sampling completes
+    # Progress update after first sampling completes (no yield to avoid showing old QR)
     msg = f"First pass sampling complete... decoding image (step {current_step}/{total_steps})"
     log_progress(msg, gr_progress, 0.4)
-    yield (noisy_qr_pil if border_size > 0 else base_qr_pil, msg)
+    # Removed yield here - caused flash of old QR before decoded image
 
     # First decode with dynamic tiling - disable for now
     # tile_size, overlap = calculate_vae_tile_size(image_size)
@@ -2458,10 +2458,10 @@ def _pipeline_artistic(
             latent_image=get_value_at_index(upscaled_latent, 0),
         )
 
-    # Yield progress update after second sampling completes
+    # Progress update after second sampling completes (no yield to avoid showing first pass)
     msg = f"Second pass sampling complete... decoding final image (step {current_step}/{total_steps})"
     log_progress(msg, gr_progress, 0.8)
-    yield (first_pass_pil, msg)
+    # Removed yield here - caused flash of first pass image before final decoded
 
     # Final decode with dynamic tiling
     tile_size, overlap = calculate_vae_tile_size(image_size)