Fix Microsoft Store taskbar icon

[FaulMit]

Summary

• remove opaque backing plate from Captail application icon
• add complete default, dark, and light MSIX target-size icon variants
• enlarge and deepen taskbar icon color for legibility
• validate icon transparency and canvas coverage during Store builds
• support internal MSIX revisions so visible version 0.2.1 can ship as package 0.2.1.1

Validation

• built and unpacked Captail 0.2.1.1 MSIX locally
• validated Store lifecycle, FFmpeg isolation, native dependencies, and 45 icon variants
• confirmed MSIX identity 0.2.1.1 with Captail product version 0.2.1

No GitHub Release will be created for this Store-only fix.