Turbopack not parsing `${configDir}` used in extended base tsconfig.json leads to errors

### Link to the code that reproduces this issue https://github.com/eliw00d/next-turbopack-configdir-repro ### To Reproduce 1. From root, run `rush update && rush build` 2. Notice that `app-with-error` fails because of `Import map: aliased to relative './components/Center' inside of [project]/rigs/web-rig/profiles/default/config/typescript/${configDir}/src` ### Current vs. Expected behavior Current behavior --- Building a Next.js app that extends another tsconfig.json does not parse `${configDir}` and throws errors related to the import map. Expected behavior --- Building a Next.js app that extends another tsconfig.json parses `${configDir}` and builds successfully. ### Provide environment information ```bash Operating System: Platform: linux Arch: x64 Version: #1 SMP PREEMPT_DYNAMIC Thu Jun 5 18:30:46 UTC 2025 Available memory (MB): 31923 Available CPU cores: 16 Binaries: Node: 22.21.1 npm: 10.9.4 Yarn: N/A pnpm: N/A Relevant Packages: next: 16.0.3 // Latest available version is detected (16.0.3). eslint-config-next: N/A react: 19.2.0 react-dom: 19.2.0 typescript: 5.9.3 Next.js Config: output: N/A ``` ### Which area(s) are affected? (Select all that apply) Turbopack ### Which stage(s) are affected? (Select all that apply) next dev (local), next build (local), next start (local) ### Additional context _No response_