feat: switch site contact email to ceo@, add WhatsApp hotline

Replaces hello@auraajenticai.cloud with ceo@auraajenticai.cloud across every
display/mailto surface (nav CTA, contact page, direct-contact card, JSON-LD),
and adds +8801911877091 as a real WhatsApp contact channel (click-to-chat
link on the Contact page and the home page's Direct card, plus telephone in
the Organization schema). The contact form itself is unaffected — it already
posts to a separate address via formsubmit.co, not through this email.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/nav.jsx

@@ -127,7 +127,7 @@ const Nav = ({ onCmdK, theme, onToggleTheme, accent, lang, onToggleLang, route }
               {lang === "en" ? "বাং" : "EN"}
             </button>
 
-            <a href="mailto:hello@auraajenticai.cloud?subject=Project Quote" className="nav-quote-btn" style={{
+            <a href="mailto:ceo@auraajenticai.cloud?subject=Project Quote" className="nav-quote-btn" style={{
               padding: "7px 13px",
               background: "transparent",
               border: "1px solid var(--line)",
@@ -262,7 +262,7 @@ const Nav = ({ onCmdK, theme, onToggleTheme, accent, lang, onToggleLang, route }
               {lang === "en" ? "বাংলা" : "English"}
             </button>
             <a
-              href="mailto:hello@auraajenticai.cloud?subject=Project Quote"
+              href="mailto:ceo@auraajenticai.cloud?subject=Project Quote"
               onClick={() => setMenuOpen(false)}
               style={{
                 padding: "8px 14px",