ci: add a non-blocking Windows test lane for the shipped CLIs (#228)

We ship `gl` and `git-remote-gitlawb` to Windows users via release.yml but run
no Windows tests: pr-checks.yml is ubuntu-only, and the single windows-latest in
the repo is the release build step, which never runs `cargo test`. So changes to
the shipped Windows CLIs (e.g. the multi-round fetch fix in #192) reach Windows
users with zero test runs on Windows.

Add a `test-windows` job that runs `cargo test -p gl -p git-remote-gitlawb` on
windows-latest with `continue-on-error: true`, mirroring the informational beta
lane: a Windows-only failure is visible on the PR but does not block merge. The
two crates are the client CLIs and depend on no database, so the job needs no
Postgres service (service containers do not run on windows-latest regardless);
git is preinstalled on the runner for the real_git_fetch harness.

This makes the #[cfg(windows)] regressions from #192 load-bearing instead of
never-run. Un-gating the currently #[cfg(unix)] harness tests is the deferred
follow-on in #228.

Author: t

.github/workflows/pr-checks.yml

@@ -216,3 +216,34 @@ jobs:
 
       - name: Smoke test --version
         run: docker run --rm gitlawb-node:ci-test --version
+
+  test-windows:
+    name: test (windows, non-blocking)
+    runs-on: windows-latest
+    timeout-minutes: 45
+    # Non-blocking, mirroring the informational `beta` lane above. We ship `gl`
+    # and `git-remote-gitlawb` to Windows users (release.yml) with zero Windows
+    # test coverage, so run their suites here to make Windows-only regressions
+    # VISIBLE on the PR without gating merge (#228). These two are the client
+    # CLIs and depend on no database, so no Postgres service is needed (service
+    # containers do not run on windows-latest regardless). `git` is preinstalled
+    # on windows-latest, which the real_git_fetch harness relies on.
+    continue-on-error: true
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          persist-credentials: false
+
+      - name: Set up Rust toolchain
+        uses: dtolnay/rust-toolchain@b3b07ba8b418998c39fb20f53e8b695cdcc8de1b # stable
+        with:
+          toolchain: stable
+
+      - name: Cache cargo
+        uses: Swatinem/rust-cache@98c8021b550208e191a6a3145459bfc9fb29c4c0 # v2.8.0
+        with:
+          key: windows
+
+      - name: cargo test (shipped Windows crates)
+        run: cargo test -p gl -p git-remote-gitlawb