- Rename index.rs to database.rs for clarity in purpose

- Update references in `scan.rs` to the renamed module
- Add `cargo clippy` step to CI for linting

.github/workflows/rust.yml

@@ -18,5 +18,7 @@ jobs:
     - uses: actions/checkout@v4
     - name: Build
       run: cargo build --verbose
+    - name: Run linter
+      run: cargo clippy --all-targets --all-features -- -D warnings
     - name: Run tests
       run: cargo test --verbose