ci: add GitHub Actions workflow for contracts and frontend

.github/workflows/ci.yml

@@ -0,0 +1,65 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  contracts:
+    name: Contracts (build · clippy · test)
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: contracts
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: wasm32-unknown-unknown
+          components: rustfmt, clippy
+
+      - uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: contracts
+
+      - name: Format check
+        run: cargo fmt --all -- --check
+
+      - name: Clippy
+        run: cargo clippy --all-targets -- -D warnings
+
+      - name: Test
+        run: cargo test
+
+      - name: Build WASM
+        run: cargo build --release --target wasm32-unknown-unknown
+
+  frontend:
+    name: Frontend (typecheck · lint · build)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: pnpm/action-setup@v4
+        with:
+          version: 9
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: pnpm
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      - name: Typecheck
+        run: pnpm -r run typecheck
+
+      - name: Lint
+        run: pnpm --filter frontend lint
+
+      - name: Build
+        run: pnpm build