[Bug]: pnpm install fails on Windows when the user profile name is non-ASCII — node-gyp writes binding.sln without a BOM

### Operating system

Windows

### Orca version

1.4.194 (`main` @ f088872554)

### Details

`pnpm install` cannot finish on a Windows machine whose user profile name contains non-ASCII characters. The postinstall native rebuild fails every time:

```
[rebuild] Patched node-pty build artifacts are missing; rebuilding from source.
...\node-pty\build\binding.sln(12): solution file error MSB5013: An error occurred while parsing the project section.
Error: MSBuild.exe failed with exit code: 1
[rebuild] Native module rebuild failed: node-gyp failed to rebuild '...node-pty'
```

### Root cause

node-gyp resolves `node-addon-api` through pnpm's store with a relative path that walks up out of the package:

```
"..\..\..\..\node-addon-api@7.1.1\node_modules\node-addon-api\node_addon_api_except.vcxproj"
```

and emits a solution-folder node for every segment of that walk. On this machine that includes the user profile directory, so `binding.sln` line 12 is:

```
Project("{2150E333-...}") = "()", "..\Users\", "{917AF3A5-...}"
```

The file is written as UTF-8 **without a BOM**. MSBuild falls back to the system ANSI code page (949 here) when a solution file has no BOM, so those bytes decode to mojibake and the project section fails to parse.

Nothing about the module is wrong — it is purely the generated solution file being unreadable in the active code page.

### Confirmed fix and workaround

Splitting the rebuild and adding the BOM between the two phases builds cleanly:

```bash
cd node_modules/.pnpm/node-pty@1.1.0_patch_hash=*/node_modules/node-pty
npx node-gyp configure
python -c "import io;p='build/binding.sln';r=io.open(p,'rb').read();io.open(p,'wb').write(b'\xef\xbb\xbf'+r)"
npx node-gyp build # -> build/Release/conpty.node
```

That produces the artifact, so **the missing BOM is the whole problem**.

The workaround does not survive, though: `pnpm install` / `pnpm build` re-enter `rebuild-native-deps.mjs`, and `node-gyp rebuild` cleans before it configures, so the patched solution file and the built `.node` are both discarded and the next run fails the same way.

### Why I did not open a PR

`config/scripts/rebuild-native-deps.mjs` delegates the whole build to `@electron/rebuild`:

```js
await rebuild({ ... }) // the only build invocation in the script
```

which calls `node-gyp rebuild` (clean → configure → build) internally. There is no seam between configure and build to insert the BOM, and pre-writing the file does not help because the clean step removes it. A real fix looks like it belongs in node-gyp — write the solution file with a BOM, or ASCII-escape the generated folder names — rather than in this repo.

Filing it here because it blocks `pnpm install` outright for anyone in this situation, and the two encoding failures are not obvious from the error text alone — the diagnosis may save the next person the search.

### Repro

1. On Windows, use a user profile whose name contains non-ASCII characters (Korean here; any CP-non-representable name should do).
2. Clone the repo under that profile and run `pnpm install`.
3. postinstall fails with `MSB5013` on `binding.sln`.

### Environment

Windows 11 (10.0.26200), system code page 949, Node 24, VS 2022 Build Tools, pnpm workspace install.