Fix planner production server + use .ts extensions everywhere

- Fix createRequestHandler → createRequestListener (@react-router/node
  removed the old API)
- Move noEmit + allowImportingTsExtensions to tsconfig.base.json so all
  packages and apps inherit them consistently
- Add explicit .ts extensions to all remaining relative imports across
  packages and apps

Verified locally: node --experimental-strip-types server.ts starts and
responds 200.

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

packages/gpx/src/generate.test.ts

@@ -1,6 +1,6 @@
 import { describe, it, expect } from "vitest";
-import { generateGpx } from "./generate";
-import { parseGpx } from "./parse";
+import { generateGpx } from "./generate.ts";
+import { parseGpx } from "./parse.ts";
 
 describe("generateGpx", () => {
   it("generates valid GPX with name", () => {