Use official Omarchy mark in app branding

[tcballard]

Summary

• replace the app icon's custom play-mark artwork with the official Omarchy mark
• preserve the existing 1024 px canvas, dark rounded tile, color, proportional scaling, and safe margin
• document the official source and keep the project's independent status explicit

This deliberately retains the icon pipeline and outer treatment introduced in #87; only the central symbol changes.

Brand provenance

The mark is copied without redrawing or recoloring from omacom/omarchy-site@70d4015, published through the official Omarchy brand page. The source SVG SHA-256 is 4d00403ea7796c1fcd9a1574f807203f8d17f94d7c7fe90045963cf150346f70.

The README continues to state that Try Omarchy is not official or affiliated with Omarchy and notes that the mark remains subject to Omarchy's trademark rights.

Verification

• git diff --check
• parsed the source and adapted SVGs and confirmed the official path data and #9ece6a fill are exact
• rendered the 1024 px source successfully
• visually inspected full-size output and light, dark, and checkerboard previews at 16, 32, 64, 128, and 256 px
• confirmed 98 px outer tile clearance on every edge

make test could not be run in the local Linux workspace because this project's required Swift/AppKit environment is macOS. Hosted CI should provide the authoritative macOS test result for this exact branch.