refactor: minimal dark dashboard redesign

[Kwickos]

Restyles the test dashboard toward a clean, minimal dark UI (SaaS-style reference).

Changed

• Sidebar navigation (Overview / Matches / Game inspector / Live console / Requests / Roadmap) with view switching — one focused view at a time instead of a long scroll.
• Neutral dark palette with a single soft indigo accent; semantic colors only on chips (status, event types).
• Soft rounded cards, subtle 1px borders, Plus Jakarta Sans for UI (mono reserved for IDs, console and request log).
• Segmented status filter on Matches; league rows with logo placeholders; latest-frame shown as key-value items.
• Removed the neon/glow/grid 'control room' styling.
• Same functionality and API contract as before (overview stats, pagination, inspector timeline + gold sparkline, WS console, request log, roadmap).

Verified

• pytest 16/16 · JS syntax-checked (node) · served live: HTTP 200, real data (matches incl. MSI) rendered.