v1.5.4

Fix window icon (fourth attempt — different root cause than assumed).

Previous attempts all used ICO format via wm_iconbitmap, which was silently failing in the PyInstaller bundle at runtime. Root cause: tk's wm iconbitmap appears to reject the encoded ICO, the exception is swallowed, and CTk's default blue square wins.

New approach:

• Generate a 16×16 RGBA PNG at runtime using stdlib struct + zlib (no encoding surprises — structurally guaranteed valid)
• Block CTk's scheduled after(200) callback by setting _iconbitmap_method_called = True immediately after super().__init__()
• Set icon via iconphoto() with the generated PhotoImage (PNG-native in Tk 8.6+, which ships with all modern Python/Windows builds)