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>

instrumentation-client.ts

@@ -1,12 +1,2 @@
-// This file configures the initialization of Sentry on the client.
-// The added config here will be used whenever a users loads a page in their browser.
-// https://docs.sentry.io/platforms/javascript/guides/nextjs/
-
-import * as Sentry from "@sentry/nextjs";
-
-Sentry.init({
-  dsn: process.env.NEXT_PUBLIC_SENTRY_DSN || "https://148e31ea874c60f3d2e0f70fd6701f6b@o4510751135105024.ingest.de.sentry.io/4510751388926032",
-  enabled: false,
-});
-
-export const onRouterTransitionStart = Sentry.captureRouterTransitionStart;
+// Sentry client SDK disabled to reduce bundle size (~400KB).
+// To re-enable, restore the @sentry/nextjs import and withSentryConfig in next.config.ts.