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/server.ts

@@ -1,9 +1,16 @@
+import * as Sentry from "@sentry/node";
 import { createRequestListener } from "@react-router/node";
 import { createServer, type IncomingMessage, type ServerResponse } from "node:http";
 import { createReadStream, statSync } from "node:fs";
 import { join, extname, resolve } from "node:path";
 import { setupYjsWebSocket } from "./app/lib/yjs-server.ts";
 
+Sentry.init({
+  dsn: "https://5215134cd78d5e6c199e29300b8425af@o4509530546634752.ingest.de.sentry.io/4511102546608208",
+  tracesSampleRate: 0.1,
+  enabled: process.env.NODE_ENV === "production",
+});
+
 const port = Number(process.env.PORT ?? 3001);
 const CLIENT_DIR = resolve(import.meta.dirname, "build", "client");