feat: add windows runner CI and release jobs

.forgejo/workflows/ci.yml

@@ -66,3 +66,30 @@ jobs:
         working-directory: carrier
         env:
           GITHUB_TOKEN: ""
+
+  windows:
+    runs-on: windows-x86_64
+    steps:
+      - uses: https://code.forgejo.org/actions/checkout@v4
+        with:
+          path: carrier
+      - uses: https://code.forgejo.org/actions/checkout@v4
+        with:
+          repository: randogoth/fumi
+          ref: main
+          path: fumi
+      - uses: https://code.forgejo.org/actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry
+            carrier/target
+            fumi/target
+          key: cargo-windows-${{ hashFiles('carrier/Cargo.lock') }}
+          restore-keys: cargo-windows-
+      # No devbox on Windows: the runner host itself is the MSYS2 MINGW64
+      # toolchain that windows/setup.sh installs, so this runs the same
+      # commands devbox's `check` script runs on the other two platforms
+      # straight from cargo.
+      - run: cargo fmt --check && cargo build && cargo test
+        working-directory: carrier
+        shell: bash