Update UI with eye-friendly colour scheme

Replace bright white backgrounds with warmer off-white tones to reduce
eye strain while maintaining good contrast and professional appearance.

Changes:
- Update CSS variables with warmer neutral palette (#f5f3f0 page bg,
  #faf9f7 surfaces, #f0ede8 muted sections)
- Soften primary blue from #2563eb to #3b6fd4
- Update navbar, cards, tables to use new surface colours
- Update upload area, file lists, and icon backgrounds
- Update flag item backgrounds with softer tints
- Update shared components (VeracityScoreCard, FlagsList)

The new colour scheme uses warm off-white/cream tones that are easier
on the eyes than pure white while maintaining professionalism.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/TrueCV.Web/Components/Pages/Home.razor

@@ -29,7 +29,7 @@
 </section>
 
 <!-- Features Section -->
-<section id="features" class="py-5 bg-light">
+<section id="features" class="py-5" style="background-color: var(--truecv-bg-muted);">
     <div class="container">
         <div class="text-center mb-5">
             <h2 class="fw-bold">How TrueCV Works</h2>