fix: resolve overlapping group bounding boxes and add README

Group 4/5 and Group 1/2 bounding boxes overlapped, causing nodes to
appear in multiple groups. Muting the Seam Fix group would have also
muted Pass 1 output nodes. Repositioned GenerateSeamMask node and
adjusted all group boundaries to eliminate overlaps.

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

example_workflows/tiled-upscale-builtin-nodes.json

@@ -235,7 +235,7 @@
     {
       "id": 13,
       "type": "GenerateSeamMask",
-      "pos": [2040, 500],
+      "pos": [2370, 650],
       "size": [250, 170],
       "flags": {},
       "order": 12,
@@ -453,7 +453,7 @@
     {
       "id": 1,
       "title": "Load Models",
-      "bounding": [40, 130, 345, 400],
+      "bounding": [40, 130, 345, 190],
       "color": "#3f789e",
       "font_size": 24,
       "flags": {}
@@ -477,7 +477,7 @@
     {
       "id": 4,
       "title": "Pass 1: Tiled Redraw",
-      "bounding": [1150, 130, 970, 730],
+      "bounding": [1150, 130, 1200, 730],
       "color": "#3a7e3a",
       "font_size": 24,
       "flags": {}
@@ -485,7 +485,7 @@
     {
       "id": 5,
       "title": "Pass 2: Seam Fix (bypass/mute to skip)",
-      "bounding": [2030, 130, 1800, 600],
+      "bounding": [2360, 130, 1470, 710],
       "color": "#7e3a3a",
       "font_size": 24,
       "flags": {}