PM-6555: Match Marathon Matches, Archive, and Work App icons to Figma

[jmgasper]

Fixes the three icon mismatches reported in PM-6555 QA feedback: Marathon Matches now uses the angled running shoe, Archive uses the stacked tray, and Work App uses the crossed screwdriver and hammer from the Figma design.

The standalone SVGs and shared sprite use the exact exported glyph paths and colors, with the original 20×20 glyphs centered in the existing 32×32 tiles. The icon README records the Figma source nodes and sizing.

Validation:

• npm run lint: 0 errors, 0 warnings.
• npm test: all 10 tests passed.
• npm run build with uni-nav.env.dev: navigation, type declarations, and nudge builds passed.
• Headless Chromium at 1440px and 390px with staff and talent roles: each applicable icon was visually checked against the Figma export at 2× resolution (mean pixel difference below 0.5/255, allowing for SVG rasterization), renders in a 32×32 tile, and produces no browser errors. Profile responses were mocked locally.
• Verified standalone SVG/sprite parity, built asset parity, and that only the three requested symbols changed.

The separate QA question about staff access to linked applications needs a product decision on role visibility; this PR is scoped to the three numbered icon defects. Administrator drawer visibility was already addressed by #420.