fix: add PreviewImage after Pass 1 for bypass support

SaveImage was only connected to the seam fix output, so muting the
seam fix section produced no output at all. Added PreviewImage after
Pass 1's ImageMergeTileList so the user always sees the tiled redraw
result, even when the seam fix section is bypassed.

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

example_workflows/tiled-upscale-builtin-nodes.json

@@ -1,6 +1,6 @@
 {
-  "last_node_id": 22,
+  "last_node_id": 23,
-  "last_link_id": 36,
+  "last_link_id": 37,
   "nodes": [
     {
       "id": 1,
@@ -212,11 +212,26 @@
         {"name": "final_height", "type": "INT", "link": 19, "widget": {"name": "final_height"}}
       ],
       "outputs": [
-        {"name": "IMAGE", "type": "IMAGE", "slot_index": 0, "links": [25]}
+        {"name": "IMAGE", "type": "IMAGE", "slot_index": 0, "links": [25, 37]}
       ],
       "properties": {"Node name for S&R": "ImageMergeTileList"},
       "widgets_values": [2048, 2048, 128]
     },
+    {
+      "id": 23,
+      "type": "PreviewImage",
+      "pos": [2040, 350],
+      "size": [300, 300],
+      "flags": {},
+      "order": 22,
+      "mode": 0,
+      "inputs": [
+        {"name": "images", "type": "IMAGE", "link": 37}
+      ],
+      "outputs": [],
+      "properties": {"Node name for S&R": "PreviewImage"},
+      "widgets_values": []
+    },
     {
       "id": 13,
       "type": "GenerateSeamMask",
@@ -431,7 +446,8 @@
     [33, 19, 0, 20, 0, "LATENT"],
     [34, 20, 0, 21, 0, "IMAGE"],
     [35, 7, 0, 21, 1, "INT"],
-    [36, 7, 1, 21, 2, "INT"]
+    [36, 7, 1, 21, 2, "INT"],
+    [37, 12, 0, 23, 0, "IMAGE"]
   ],
   "groups": [
     {