feat: brand logo overhaul, matte UI theme, dynamic theming, and layout inspector

[spelech]

Summary

This pull request introduces the monochromatic L³M² brand identity, overhauls the Avalonia XAML styling with a modern matte carbon design system, adds a live runtime dynamic theming engine, and integrates \playwright-layout-inspector\ for automated visual and responsive audits.

Key Changes

1. Brand Identity & Icon Assets:
   • Monochromatic \L³M²\ squircle vector mark (\Assets/logo.svg).
   • Multi-resolution Windows ICO (\Assets/app-icon.ico), 512px master PNG (\Assets/app-icon.png), 128px tray icon (\Assets/app_tray_icon.jpg), and WASM favicons.
   • Updated web metadata and title in \index.html.
2. Matte UI Design System:
   • Replaced neon purple/cyan gradients and heavy glows with high-contrast matte carbon/slate tokens (#0d1117, #161b22, #1c2128, #30363d) in \DesignTokens.axaml\ and \MatteTheme.axaml.
   • Maintained backward-compatible aliases for legacy theme styles.
3. Control Layout Modernization:
   • Streamlined \TelemetryHeaderControl.axaml\ into 3 compact horizontal hardware chips (CPU, RAM, GPU VRAM, and service health dots).
   • Segmented pill tab navigation in \MainView.axaml\ and standardized card containers across all sub-views.
4. Dynamic / Live Theming Engine:
   • Implemented \IThemeService\ and \ThemeService\ with in-place \SolidColorBrush\ mutation for instant live theme switching across Desktop and WASM.
   • Supports \MatteCarbon\ (Default Dark), \OledBlack\ (Pure Black), and \Clean Light\ modes.
   • Two-way bound to \SettingsViewModel\ and selectable via \SettingsTabControl.axaml.
5. Playwright Layout Inspector Integration:
   • Configured Node/TypeScript tooling with ESLint 9, strict TypeScript, and \github:spelech/playwright-layout-inspector.
   • Layout audit suite (\ ests/layout-inspector/layout-audit.spec.ts) auditing Desktop (1080p/1440p), iPad Tablet, and Galaxy S25+ Mobile viewports.

Verification

• 
  pm run lint: 0 errors
• 
  px tsc --noEmit: 0 type errors
• \dotnet test LocalLLMServerManager.sln: 180 passed, 0 failed, 1 skipped