bug: resolve TypeScript 7 build breakage caused by tsup/rollup-plugin-dts incompatibility during d.ts generation

## 1. Symptom

Running `pnpm build` fails with multiple package tasks aborted by the same runtime error:

- Error:
- `TypeError [Error]: Cannot read properties of undefined (reading 'useCaseSensitiveFileNames')`
- Stack root:
- `node_modules/tsup/dist/rollup.js -> .../rollup-plugin-dts/dist/rollup-plugin-dts.cjs`
- Build shape:
- Bundling (`ESM/CJS`) starts successfully.
- Failure happens when d.ts-related rollup phase is initialized.

```log
Error [ERR_PACKAGE_PATH_NOT_EXPORTED]: No "exports" main defined in ~/node_modules/~/package.json
at exportsNotFound (node:internal/modules/esm/resolve:314:10)
at packageExportsResolve (node:internal/modules/esm/resolve:661:9)
at resolveExports (node:internal/modules/cjs/loader:639:36)
at Function._findPath (node:internal/modules/cjs/loader:728:31)
at Function._resolveFilename (node:internal/modules/cjs/loader:1211:27)
at Function.resolve (node:internal/modules/helpers:146:19)
at resolveTsConfigFromExtends (~/node_modules/load-tsconfig/d
ist/index.cjs:163:18)
at loadTsConfigInternal (~/node_modules/load-tsconfig/dist/in
dex.cjs:169:26)
at loadTsConfigInternal (~/node_modules/load-tsconfig/dist/in
dex.cjs:185:28)
at loadTsConfigInternal (~/node_modules/load-tsconfig/dist/in
dex.cjs:185:28)
```

---

## 2. Current Environment

- Tooling:
- Node: `v22.14.0` (from log)
- `pnpm@10.20.0`
- `turbo@2.10.4`
- `tsup@8.5.1`
- Root dependency:
- `typescript: "7.0.2"`
- Forced version:
- `overrides: { "typescript": "7.0.2" }`

---

## 3. How it happens

1. Install root dependencies and run `pnpm build`.
2. Turbo runs package `build` tasks in parallel.
3. `tsup` compiles JS output for multiple packages successfully.
4. In packages with `dts: true`, `tsup` internally invokes rollup + `rollup-plugin-dts`.
5. `rollup-plugin-dts` path in runtime points to:
- `node_modules/.pnpm/rollup-plugin-dts@6.1.1_rollup@4.53.2_typescript@5.7.3/node_modules/...`
6. The plugin crashes accessing `useCaseSensitiveFileNames` on an undefined object, aborting build.

```tsup.config.ts
import { defineConfig } from 'tsup'

export default defineConfig((options) => ({
entry: {
index: 'src/index.ts',
},
watch: options.watch ? ['src/**/*'] : false,
clean: false,
dts: true,
outDir: 'dist',
target: 'esnext',
format: ['cjs', 'esm'],
sourcemap: false,
}))
```

---

## 4. Root cause analysis and suggestion

I think this is a **toolchain compatibility regression**, not library code.

- `tsup` in this repo is pinned to `8.5.1`, whose runtime bundle references `rollup-plugin-dts@6.1.1`.
- In the active lock and logs, `rollup-plugin-dts` is resolved with a TypeScript variant tied to `5.7.3`, while the project root is forcing `typescript@7.0.2`.
- `rollup-plugin-dts@6.1.1` is not aligned with TypeScript 7 API expectations in this environment (or gets passed undefined due to internal resolution mismatch), producing the `useCaseSensitiveFileNames` failure.

So the failure is caused by mixed toolchain state:
- Project-level TS = 7.0.2
- tsup+dts internal plugin bundle = TS-linked older expectations (5.7.3-like compatibility path)

This is why only build-time declaration generation is impacted, while TS transpilation itself appears to complete.

Reproduce the failure with `pnpm build`, then inspect the shown `tsup.config.ts` and the active lock resolution for tsup, rollup-plugin-dts, and TypeScript. Compare the versions involved in packages using `dts: true`; done means declaration generation completes across the affected package build tasks without the reported runtime error.

Written by the indexing model from the issue text.