Add Sentry error tracking to both apps

Planner (client + custom server) and Journal (client + entry.server):
- Client: @sentry/react with browser tracing + replay on error
- Server: @sentry/node for unhandled exceptions
- ErrorBoundary captures React errors via Sentry.captureException
- Disabled in dev, 10% trace sample rate in production

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

apps/planner/app/entry.client.tsx

@@ -0,0 +1,22 @@
+import * as Sentry from "@sentry/react";
+import { startTransition, StrictMode } from "react";
+import { hydrateRoot } from "react-dom/client";
+import { HydratedRouter } from "react-router/dom";
+
+Sentry.init({
+  dsn: "https://5215134cd78d5e6c199e29300b8425af@o4509530546634752.ingest.de.sentry.io/4511102546608208",
+  integrations: [Sentry.browserTracingIntegration(), Sentry.replayIntegration()],
+  tracesSampleRate: 0.1,
+  replaysSessionSampleRate: 0,
+  replaysOnErrorSampleRate: 1.0,
+  enabled: import.meta.env.PROD,
+});
+
+startTransition(() => {
+  hydrateRoot(
+    document,
+    <StrictMode>
+      <HydratedRouter />
+    </StrictMode>,
+  );
+});