Restyle to a clean, flat look and rename brand to SCOPENET

- Brand is now SCOPENET everywhere (defaults, UI, installer, docs)
- Launcher: solid backgrounds (no animated orbs/grain), flat Play button
  without gradient/shine/glow, quieter rail with a simple active
  indicator, smaller type scale, Inter as default font, glass off by
  default, restyled sliders
- Panel: same flat treatment; live preview mirrors the new launcher
- New flat scope-reticle logo and app icons
- Calmer default palette
- Fix: lock the shared cargo cache in the Docker build (amd64/arm64 raced)
- Fix: Windows-only clippy lint in sys.rs

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011ARcGWxLx21FwXJ3yfGriS

panel/web/src/components/BarChart.svelte

@@ -66,7 +66,7 @@
   svg { width: 100%; height: auto; display: block; overflow: visible; }
   .grid { stroke: rgba(255, 255, 255, 0.06); stroke-width: 1; }
   .tick { fill: var(--muted); font-size: 11px; font-family: var(--font); }
-  .bar { fill: #8b6cff; transition: opacity 0.15s; }
+  .bar { fill: #6d6af5; transition: opacity 0.15s; }
   .bar.dim { opacity: 0.4; }
   .tip {
     position: absolute; transform: translate(-50%, calc(-100% - 10px)); pointer-events: none; background: var(--surface-3);