feat(studio-desktop): n/ax namespace logo (app icon + tray) (#526)

The "n/ax" namespace mark (necmttn/ax path lockup): gray "n", leaning blue "/"
accent, white "ax", on the dark squircle. Drawn as real SVG glyph OUTLINES
(Arial Bold/Bold-Italic extracted to paths) - font-independent, crisp at every
size, with hand-tuned spacing (not font kerning). Tray = bold monochrome "ax"
(n/ax is illegible at 16px menubar). Replaces the ascending-bars placeholder.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: Necmttn