Fix blurry tray icon at fractional DPI scales

[Gabriel Dufresne (GabrielDuf)]

Added the missing 20, 28, 36, 40 px frames to all 10 tray state×theme icons ({empty,blue,green,orange,turquoise} × {black,white}), so every fractional scale up to 250% has an exact
match.

• New frames are downscaled from each file's own 96px frame (high-quality bicubic), stored as 32bpp DIB to match the existing format.
• Existing 6 frames are preserved byte-for-byte — only the 4 sizes are appended.
• No code changes — TrayService.cs and the Avalonia load path are unchanged.