Harden installer icon + NSIS rebuild path

- Regenerate icon.ico with classic BMP entries (16/32/48) — PNG-compressed
  ICO entries can fail NSIS' icon loader on some builds
- CI copies assets/textures/icon.ico onto the packaging path right before
  makensis, removing any stale/missing-copy failures
- Recreate v0.2.1 tag after this fix

tools/generate_textures.py

@@ -306,12 +306,12 @@ def app_icon():
     icon("icon.png", badge, size=1024)
     icon("icon.ico", badge, size=256)
 
-    # multi-size ICO for Windows (from the 256 render)
-    src = Image.open(os.path.join(ASSETS, "icon.png"))
+    # ICO for Windows. Sizes stay at 16/32/48 so every entry uses classic BMP
+    # (PNG-compressed entries, used by PIL at >=256px, break some NSIS builds).
+    src = Image.open(os.path.join(ASSETS, "icon.png")).convert("RGBA")
     ico_path = os.path.join(ASSETS, "icon.ico")
-    src.save(ico_path, format="ICO", sizes=[
-             (256, 256), (128, 128), (64, 64), (48, 48), (32, 32), (16, 16)])
-    print("wrote assets/textures/icon.ico (multi-size)")
+    src.save(ico_path, format="ICO", sizes=[(48, 48), (32, 32), (16, 16)])
+    print("wrote assets/textures/icon.ico (BMP 16/32/48)")
 
 
 def cards():