Prepare GitHub alpha launch (README, CI, tests, release workflow)

.github/workflows/ci.yml

@@ -0,0 +1,34 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  checks:
+    name: Rust Checks
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rustfmt, clippy
+
+      - name: Cache cargo artifacts
+        uses: Swatinem/rust-cache@v2
+
+      - name: Format check
+        run: cargo fmt --check
+
+      - name: Clippy
+        run: cargo clippy --all-targets --all-features -- -D warnings
+
+      - name: Unit tests
+        run: cargo test
+
+      - name: Cargo check
+        run: cargo check