ci(windows): build node-pty from source before the win32 suites

CI proved the encoder fix on real cmd.exe -- 26/26 -- and in the same run
proved the job suite had been testing an unpatched binary. node-pty
prefers its upstream prebuild, which does not contain this patch, so
every job-object export was absent and isPtyJobOwnershipAvailable() was
false.

That guard is why the failure was loud rather than a vacuous pass, and
it is the reason the assertion exists.

Packaging was never affected: rebuild-native-deps.mjs already builds
node-pty from source for Electron and restores the ConPTY runtime files.
The gap was the node-runtime test environment only.

Not changing requiresPatchedNodePtySourceBuild's win32 exemption here.
Its premise -- that the patch is Unix-only -- is now false, but lifting
it also needs pnpm rebuild to force a source build, and I cannot
validate that on macOS and Linux from here. Recorded as a follow-up
instead of changed blind.

.github/workflows/pr.yml

@@ -618,6 +618,16 @@ jobs:
       - name: Install dependencies
         run: pnpm install --frozen-lockfile
 
+      # Why: node-pty prefers its upstream prebuild, which does not contain
+      # Orca's Windows patch, so the job-object exports would be absent and the
+      # suite below would test an unpatched binary. build_from_source removes
+      # the prebuild, and the package's postinstall restores the ConPTY runtime
+      # files that a bare node-gyp rebuild would miss.
+      - name: Rebuild node-pty from patched source
+        env:
+          npm_config_build_from_source: 'true'
+        run: pnpm rebuild node-pty
+
       - name: Test Windows-specific boundaries
         run: >-
           pnpm exec vitest run --config config/vitest.config.ts