Add CI workflow

Runs cargo fmt --check, clippy (-D warnings), and cargo test on every
push/PR, plus a separate job verifying the wasm32v1-none release build.

Author: chonilius

.github/workflows/ci.yml

@@ -0,0 +1,36 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rustfmt, clippy
+
+      - uses: Swatinem/rust-cache@v2
+
+      - run: cargo fmt --check
+      - run: cargo clippy --workspace --all-targets -- -D warnings
+      - run: cargo test --workspace
+
+  wasm-build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: wasm32v1-none
+
+      - uses: Swatinem/rust-cache@v2
+
+      - run: cargo build --target wasm32v1-none --release