Fix warning text contrast for better readability

Change text-warning from bright yellow (#ffc107) to darker amber (#b45309)
for WCAG AA compliant 4.8:1 contrast ratio on white backgrounds.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/TrueCV.Web/wwwroot/app.css

@@ -863,6 +863,10 @@ h1:focus {
     color: var(--truecv-gray-600) !important;
 }
 
+.text-warning {
+    color: #b45309 !important; /* Darker amber for better contrast on white (4.8:1 ratio) */
+}
+
 /* Row selection highlight */
 .table tbody tr.selected {
     background-color: rgba(37, 99, 235, 0.08) !important;