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/root.tsx

@@ -1,6 +1,7 @@
 import { Links, Meta, Outlet, Scripts, ScrollRestoration, isRouteErrorResponse } from "react-router";
 import type { LinksFunction } from "react-router";
 import type { Route } from "./+types/root";
+import * as Sentry from "@sentry/react";
 import stylesheet from "@trails-cool/ui/styles.css?url";
 
 export const links: LinksFunction = () => [{ rel: "stylesheet", href: stylesheet }];
@@ -28,6 +29,8 @@ export default function App() {
 }
 
 export function ErrorBoundary({ error }: Route.ErrorBoundaryProps) {
+  Sentry.captureException(error);
+
   if (isRouteErrorResponse(error)) {
     return (
       <div className="flex h-full items-center justify-center">