perf: remove Sentry client SDK and lazy-load TipTap (~830KB saved)

- Remove withSentryConfig wrapper from next.config.ts (Sentry was disabled anyway)
- Clear instrumentation-client.ts to prevent Sentry client bundle (~400KB)
- Lazy-load RichTextClient via next/dynamic in About.tsx and Contact.tsx
- Defers TipTap/ProseMirror loading until CMS data arrives (~430KB)
- Homepage First Load JS: 1479KB → 646KB (56% reduction)
- Shared JS: 182KB → 102KB (44% reduction)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

app/components/Contact.tsx

@@ -6,7 +6,8 @@ import { Mail, MapPin, Send, Github, Linkedin } from "lucide-react";
 import { useToast } from "@/components/Toast";
 import { useLocale, useTranslations } from "next-intl";
 import type { JSONContent } from "@tiptap/react";
-import RichTextClient from "./RichTextClient";
+import dynamic from "next/dynamic";
+const RichTextClient = dynamic(() => import("./RichTextClient"), { ssr: false });
 
 const Contact = () => {
   const { showEmailSent, showEmailError } = useToast();