fix(ci): stop the finalize Phase spawning real PowerShell on Windows

[quickbeard]

The failure

CI has been red on Windows only (Ubuntu passes every run), always on the same test:

FAIL tests/InstallApp.test.tsx > InstallApp fail-stop invariant > successful flow reaches the done screen
AssertionError: expected '…' to contain 'Happy coding'

Reproduced identically in runs 30528624379, 30540195956, 30547525224 and 30550161365.

Root cause

SetupApp's finalize Phase calls installShims(), which on Windows runs updateWindowsUserPath() → execFileSync("powershell", …) (src/lib/shims.ts:306).

Both app-level suites mock node:child_process but replace only execFile — execFileSync passes straight through to the real module. So every flow that reached finalize spawned a real, synchronous PowerShell. The runner's first such spawn is cold and blocks the event loop for ~10s, starving Ink's renders and the polling waitForFrame (which resolves silently on timeout). The app was still on ◆ Configure tools when the assertion ran.

	Ubuntu	Windows
successful flow reaches the done screen	~0.5s	11–13s
sibling finalize tests (warm PowerShell)	~0.7s	~1.5–1.9s
tests/InstallApp.test.tsx (file)	13s	49s

The same stall took ConfigApp > manual-creds happy path down in run 30540195956, along with two DoctorApp tests starved on a sibling worker.

The fix

Stub installShims in both suites that drive the finalize Phase. Nothing in either file asserts shim files, and shimsInstalled still flips true so SetupComplete's resume message is unchanged. lib/shims.test.ts already skips its own installShims block on Windows (describe.skipIf(process.platform === "win32")) for exactly this reason — the app-level tests just never got the same guard.

It also stops the suite rewriting the PATH registry entry of whatever machine runs it.

Verification

Local: pnpm fix, pnpm typecheck, pnpm test (71 files, 1254 passed), pnpm build && node dist/index.js --version → 0.5.3. The Windows matrix job on this PR is the real check.

Known, not fixed here

tests/lib/remove.test.ts calls runRemove() 16 times for real; each runs uninstallShims() → removeFromWindowsUserPath() → another real PowerShell spawn that strips ~/.codev-hub/bin from the user PATH in the registry. ~6.5s of the Windows run and a genuine side effect on a Windows dev machine, but it isn't failing and those tests assert real shim-file/rc-file removal, so it needs a more careful change than this fix warranted.

🤖 Generated with Claude Code