Added GitHub Actions CI workflow

.github/workflows/ci.yml

@@ -0,0 +1,107 @@
+name: CI
+
+on:
+  push:
+    branches: "**"
+  pull_request:
+    branches: "**"
+
+env:
+  CARGO_TERM_COLOR: always
+  RUSTFLAGS: "-D warnings"
+  RUST_MSRV: "1.70.0" # Default fallback MSRV
+
+jobs:
+  test:
+    name: Basic checks
+    strategy:
+      matrix:
+        os: [ ubuntu-latest, macos-latest, windows-latest ]
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          components: clippy, rustfmt
+
+      - name: Install cargo-deadlinks
+        run: cargo install cargo-deadlinks
+
+      - name: Build
+        run: cargo build --verbose
+
+      - name: Clippy (default features)
+        run: cargo clippy --all-targets
+
+      - name: Clippy (all features)
+        run: cargo clippy --all-features --all-targets
+
+      - name: Documentation
+        run: cargo doc --no-deps
+
+      - name: Check deadlinks
+        run: cargo deadlinks
+
+      - name: Run tests (default features)
+        run: cargo test
+
+  feature-checks:
+    name: Feature combination checks
+    strategy:
+      matrix:
+        os: [ ubuntu-latest, macos-latest, windows-latest ]
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          components: clippy, rustfmt
+
+      - name: Install cargo-hack
+        run: cargo install cargo-hack
+
+      - name: Check each feature
+        run: cargo hack check --each-feature --no-dev-deps
+
+      - name: Check feature powerset
+        run: cargo hack check --feature-powerset --no-dev-deps
+
+      - name: Clippy each feature
+        run: cargo hack clippy --each-feature --all-targets
+
+      - name: Clippy feature powerset
+        run: cargo hack clippy --feature-powerset --all-targets
+
+      - name: Test each feature
+        run: cargo hack test --each-feature
+
+      - name: Test feature powerset
+        run: cargo hack test --feature-powerset
+
+  msrv:
+    name: Check MSRV
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Get MSRV from Cargo.toml
+        run: |
+          MSRV=$(cargo metadata --no-deps --format-version 1 | jq -r '.packages[0].rust_version // "${{ env.RUST_MSRV }}"')
+          echo "MSRV=$MSRV" >> $GITHUB_ENV
+      
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@master
+        with:
+          toolchain: ${{ env.MSRV }}
+
+      - name: Debug info
+        run: |
+          echo "MSRV: $MSRV"
+          echo "Rust: $(rustc --version)"
+      
+      - name: Check MSRV
+        run: cargo check