feat(icons): adopt the new Qoder mark

[luoxuanzao]

Summary

• Replaces the old QoderIDE glyph with the monochrome mark introduced with the new Qoder app. The SVG is lifted from the new app's official vector artwork with its invisible masked detail path and duplicated fill path removed (~55 KB).
• Since the new mark is single-tone, drops the old two-tone rendering hacks: the dimmed-body opacity trick in createQoderianIconContent, the light-theme white-fill CSS patch, and the model selector backdrop stripping in createIconSvg.
• The header logo and model selector icons now follow the theme's ink tone — dark on light themes, light on dark themes — matching how the new app icon adapts, instead of brand green.
• Bumps version to 1.0.16 (1.0.15 was taken by the image-copy release).

Test plan

• npm test — 3600 tests pass (171 suites), including updated icons.test.ts assertions
• npm run build succeeds
• Rendered the new asset at 512px/48px with rsvg and pixel-compared against the official artwork (≤0.09% shape difference)
• Deployed to a local vault and verified ribbon icon, view header logo, and model selector rows on both light and dark themes