Feat/split transport

.gitattributes

@@ -0,0 +1,2 @@
+# Keep LF on every platform so dart format and byte-exact tests agree.
+* text=auto eol=lf

.github/workflows/test.yml

@@ -4,13 +4,28 @@ permissions:
   contents: read
 jobs:
   test:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
     strategy:
+      # The transport depends on platform sockets and TLS; report every OS.
+      fail-fast: false
       matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
         sdk: ['3.5.0', stable]
     steps:
       - uses: actions/checkout@d23441a48e516b6c34aea4fa41551a30e30af803
       - uses: dart-lang/setup-dart@6afc89df92d6eb3834022f73cd65adc8cdfcb92d
         with:
           sdk: ${{ matrix.sdk }}
-      - run: bash tool/check.sh
+      # doh_transport is not on pub.dev yet; resolve it from a sibling clone
+      # the same way the README describes for development.
+      - run: git clone --depth 1 --branch main https://github.com/cypherstack/doh_transport.git ../doh_transport
+        shell: bash
+      - run: |
+          cat > pubspec_overrides.yaml <<'YAML'
+          dependency_overrides:
+            doh_transport:
+              path: ../doh_transport
+          YAML
+        shell: bash
+      - run: dart tool/check.dart
+        working-directory: packages/doh_resolver