Add EN/UK/PL translations across index, footer, and why-ours pages

- index.php: translate hardcoded hero kicker, stat, explore CTA, tools
  section title/sub, and learn-more arrow; add Pricing nav link
- footer.php: fully translate tagline, privacy note, nav links, and
  disclaimer into all 4 languages via dbnToolsT()
- includes/i18n.php: 15 new keys per language (hero_kicker, footer_*,
  tools_section_*, pricing_nav_link, why_ours_trust_link, learn_more)
- translations/why-ours.php: complete uk + pl translations (70 keys each)
- assets/css/tools.css: add .lt-nav__secondary-link style

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

assets/css/tools.css

@@ -5676,6 +5676,18 @@ body.lt-landing {
   background: #0a3080;
   box-shadow: 0 6px 18px rgba(0,32,91,0.50);
 }
+.lt-nav__secondary-link {
+  display: inline-flex;
+  align-items: center;
+  color: rgba(255,255,255,0.80);
+  font-size: 0.82rem;
+  font-weight: 600;
+  text-decoration: none;
+  padding: 0 0.5rem;
+  transition: color 0.15s;
+  white-space: nowrap;
+}
+.lt-nav__secondary-link:hover { color: #fff; }
 
 /* ── Hero: logged-in CTA ─────────────────────────────────────────────────── */
 .lt-hero__auth-cta {