Initial implementation: relay server + common protocol + client stub

.github/workflows/ci.yml

@@ -0,0 +1,25 @@
+name: CI
+
+on:
+  push:
+    branches: ["main", "master"]
+  pull_request:
+
+jobs:
+  build-and-test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust (stable)
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Cache dependencies
+        uses: Swatinem/rust-cache@v2
+
+      - name: Build
+        run: cargo build --workspace --verbose
+
+      - name: Test
+        run: cargo test --workspace --verbose