fix(trip): fluid stat-value font size with clamp()

Replaces fixed 3rem with clamp(--text-sm, 5.5vw, --text-3xl) so long
values like "4:32:15" scale down on mobile instead of overflowing.
Desktop (≥870px viewport) is unchanged at 3rem.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Vgmzx8VTTTmCskSpQtsLTr

themes/intotheeast/css/style.css

@@ -601,7 +601,7 @@ body::after {
 .stat-value {
     display: block;
     font-family: var(--font-display);
-    font-size: var(--text-3xl);
+    font-size: clamp(var(--text-sm), 5.5vw, var(--text-3xl));
     font-weight: 400;
     color: var(--color-accent);
     line-height: 1.1;