ci: add GitHub Actions workflows

- Add basic CI workflow (test, build, lint)

- Add code coverage workflow with Codecov

- Configure Rust toolchain and caching

Author: Ray-Gee

.github/workflows/ci.yml

@@ -0,0 +1,52 @@
+name: CI
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    
+    - name: Install Rust
+      uses: dtolnay/rust-toolchain@stable
+      with:
+        components: rustfmt, clippy
+    
+    - name: Cache dependencies
+      uses: Swatinem/rust-cache@v2
+    
+    - name: Check formatting
+      run: cargo fmt -- --check
+    
+    - name: Clippy
+      run: cargo clippy -- -D warnings
+    
+    - name: Run tests
+      run: cargo test --verbose
+
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    
+    - name: Install Rust
+      uses: dtolnay/rust-toolchain@stable
+    
+    - name: Cache dependencies
+      uses: Swatinem/rust-cache@v2
+    
+    - name: Build
+      run: cargo build --verbose
+    
+    - name: Build (release)
+      run: cargo build --verbose --release 

.github/workflows/coverage.yml

@@ -0,0 +1,31 @@
+name: Code Coverage
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  coverage:
+    name: Code Coverage
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    
+    - name: Install Rust
+      uses: dtolnay/rust-toolchain@stable
+      with:
+        components: llvm-tools-preview
+    
+    - name: Install cargo-llvm-cov
+      run: cargo install cargo-llvm-cov
+    
+    - name: Generate code coverage
+      run: cargo llvm-cov --all-features --workspace --lcov --output-path lcov.info
+    
+    - name: Upload coverage to Codecov
+      uses: codecov/codecov-action@v3
+      with:
+        file: ./lcov.info
+        fail_ci_if_error: true