Badge gets a `radius?: string` prop to override the binary rounded/pill shape.
TopNav adds `menuToggleSize` (default 42) + `menuToggleTemplate` snippet so
consumers can tune or fully replace the hamburger. The default toggle is now
a plain `<button>` instead of fluent-button — reads as just the icon, not a
button containing one. Glyph and close-icon scale proportionally with size.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>