Add Gitea CI build workflow

.gitea/workflows/ci.yml

@@ -0,0 +1,23 @@
+name: ci
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Build relay
+        run: cargo build -p relay
+
+      - name: Build client
+        run: cargo build -p client