fix: boost global text contrast for readability

--text-secondary: #a1a1aa → #c4c4cc
--text-muted: #71717a → #8b8b96

Affects all body text, section descriptions, timeline, evidence labels,
and demo terminal dim text across the entire page.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: savvides

docs/index.html

@@ -63,8 +63,8 @@
       --bg-raised: #111118;
       --bg-card: #16161f;
       --text-primary: #e4e4e7;
-      --text-secondary: #a1a1aa;
-      --text-muted: #71717a;
+      --text-secondary: #c4c4cc;
+      --text-muted: #8b8b96;
       --accent-start: #6366f1;
       --accent-end: #a855f7;
       --border: #1e1e2e;