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>

apps/planner/app/lib/host-election.test.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect } from "vitest";
-import { electHost } from "./host-election";
+import { electHost } from "./host-election.ts";
 
 function makeStates(
   entries: Array<{ id: number; user?: boolean; role?: string }>,

apps/planner/app/lib/rate-limit.test.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect } from "vitest";
-import { checkRateLimit } from "./rate-limit";
+import { checkRateLimit } from "./rate-limit.ts";
 
 describe("checkRateLimit", () => {
   it("allows requests within limit", () => {

apps/planner/app/lib/use-routing.ts

@@ -1,7 +1,7 @@
 import { useCallback, useEffect, useRef, useState } from "react";
 import * as Y from "yjs";
-import type { YjsState } from "./use-yjs";
-import { electHost } from "./host-election";
+import type { YjsState } from "./use-yjs.ts";
+import { electHost } from "./host-election.ts";
 
 interface RouteStats {
   distance?: number;