fix: resolve all clippy warnings and convert integration_tests to custom cfg

- Add type aliases (FileRow, FolderRow, FolderRowPaginated, FolderRowOptUser) to reduce type complexity
- Simplify redundant closures in app_password_handler and webdav_handler
- Remove needless borrow in auth_handler
- Collapse nested if/let chains in login_lockout, webdav_lock, auth, rate_limit
- Box LockEntry in acquire() Err variant to fix large enum variant warning
- Rename DeviceCodeStatus::from_str to parse to avoid should_implement_trait lint
- Add #[allow(clippy::too_many_arguments)] and #[allow(clippy::result_unit_err)] where appropriate
- Convert integration_tests from cargo feature to custom cfg attribute
- Add check-cfg lint config in Cargo.toml for integration_tests cfg

src/infrastructure/services/chunked_upload_service.rs

@@ -495,13 +495,12 @@ impl ChunkedUploadService {
         // worker free for other connections.
         if let Some(ref expected_checksum) = checksum {
             let data_clone = data.clone(); // Bytes::clone is O(1) — just an Arc increment
-            let actual_checksum =
-                tokio::task::spawn_blocking(move || {
-                    use md5::{Md5, Digest};
-                    format!("{:x}", Md5::digest(&data_clone))
-                })
-                    .await
-                    .map_err(|e| format!("MD5 checksum task failed: {e}"))?;
+            let actual_checksum = tokio::task::spawn_blocking(move || {
+                use md5::{Digest, Md5};
+                format!("{:x}", Md5::digest(&data_clone))
+            })
+            .await
+            .map_err(|e| format!("MD5 checksum task failed: {e}"))?;
 
             if actual_checksum != *expected_checksum {
                 return Err(format!(