Replace CorveilBrandmark PNG with SVG for crisper rendering

[dhilgaertner]

Summary

Replace the current raster CorveilBrandmark.png with an SVG version so the brandmark renders sharp at any size (About window, theme views, hi-DPI displays).

New asset

Local file: /Users/dustinhilgaertner/Downloads/let_s_remove_the_woods_corveil_and_the_star_lookin_019da612-80c6-733b-937b-41e7a037c6b2.svg

(Drag this into the issue via the web UI if you want it attached, or drop it into Sources/Crow/Resources/ as CorveilBrandmark.svg when implementing.)

Current usage to update

• Sources/Crow/Resources/CorveilBrandmark.png — replace with CorveilBrandmark.svg
• Package.swift:39 — change .copy("Resources/CorveilBrandmark.png") to the SVG filename
• Sources/Crow/App/AboutView.swift:64 — update bundle.url(forResource: "CorveilBrandmark", withExtension: "png") to "svg"
• Packages/CrowUI/Sources/CrowUI/CorveilTheme.swift:85 — same extension update

Notes

• SwiftUI's Image doesn't load SVG from a Bundle.url the same way as PNG — may need to render via NSImage(contentsOf:) on macOS (which supports SVG natively on macOS 13+) or convert to a PDF asset in an .xcassets catalog for resolution independence. Decide on the approach during implementation.
• Verify the brandmark still looks correct against both light and dark themes once swapped in.