Improve: redraw the logo as exact geometry

[SandObserver]

Summary

• Replace the traced logo paths in the admin sidebar, the About page, the empty-dashboard mark (brand-mark.js) and favicon.svg with the logo rebuilt as geometry: centre 512,512, radius 331, 30° arms, round-capped strokes.
• Regenerate favicon.png, favicon-192.png, favicon-512.png, favicon-maskable.png and favicon.ico from the new SVG.
• Add logo, start, run and create to icon-set.js. logoIcon() builds the logo on the 24-unit grid, with single strokes for the line styles.
• Restamp the cache-busting versions.
• Add tests for the logo's parts, bounds and line-style strokes, and for the new ids.

Testing
All green, including the Docker build. Added 3 tests for the logo icon and the new ids.

Changelog

Changed

• Redraw the logo as exact geometry in the favicon, the app icons and Settings.

Checklist

• Stays within the project constraints: one container, no runtime dependencies, no build step (see CONTRIBUTING.md).
• Tests added or updated for new logic, and the full suite, lint, and typechecks pass.
• Docs updated if behavior or configuration changed.