feat(FN-2266): align PWA and favicon assets with dashboard brand mark

- Replace public logo.svg with the header ring+swoosh geometry to keep branding consistent
- Refresh icon-192.png and icon-512.png assets to match the updated dashboard mark
- Add PWA tests that validate logo.svg structure and ensure install icon files exist
- Document favicon/PWA brand alignment expectations in the dashboard README

packages/dashboard/README.md

@@ -523,6 +523,8 @@ All color themes automatically provide values for these tokens. Adding a new col
 
 **Header brand lockup:** The logo SVG and "Fusion" wordmark are wrapped in a dedicated `.header-brand` flex container with `gap: var(--space-xs)` (4 px). This isolates logo-to-wordmark spacing from the wider `.header-left` gap (`var(--space-sm)`, 8 px) so the brand mark can be tuned independently of the spacing between the brand group and adjacent header controls (project selector, back button, etc.).
 
+**Favicon and PWA icon alignment:** The public favicon (`app/public/logo.svg`) and PWA install icons (`app/public/icons/icon-192.png`, `app/public/icons/icon-512.png`) intentionally mirror the header logo geometry — the outer ring and swoosh/comet shape from `Header.tsx`. This ensures users see one consistent brand mark across the dashboard UI, browser tab favicon, and installed PWA shortcuts. The logo assets use `currentColor` for theme-driven coloring, matching the header's approach.
+
 ## Performance Characteristics
 
 The dashboard includes several runtime safeguards to stay responsive during long sessions and on larger boards: