Fix unused variable/field warnings in data_acquisition_service

Changes:
- service.rs:198: Prefix unused `end_idx` with underscore
- service.rs:26: Prefix unused `uploader` and `validator` fields with underscore
- downloader.rs:44: Prefix unused `config` field with underscore
- validator.rs:62: Prefix unused `config` field with underscore

Result: 0 warnings in data_acquisition_service
Verified: cargo check -p data_acquisition_service passes

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

services/data_acquisition_service/src/downloader.rs

@@ -41,13 +41,13 @@ pub struct DownloadJob {
 
 /// Databento API downloader
 pub struct DatabentoDownloader {
-    config: DatabentoDownloaderConfig,
+    _config: DatabentoDownloaderConfig,
 }
 
 impl DatabentoDownloader {
     /// Create new downloader
     pub fn new(config: DatabentoDownloaderConfig) -> Self {
-        Self { config }
+        Self { _config: config }
     }
 
     /// Download data for a job

services/data_acquisition_service/src/service.rs

@@ -23,8 +23,8 @@ type JobStore = Arc<RwLock<std::collections::HashMap<String, DownloadJobDetails>
 /// Data Acquisition Service implementation
 pub struct DataAcquisitionServiceImpl {
     downloader: Arc<DatabentoDownloader>,
-    uploader: Arc<MinIOUploader>,
-    validator: Arc<DataValidator>,
+    _uploader: Arc<MinIOUploader>,
+    _validator: Arc<DataValidator>,
     job_store: JobStore,
 }
 
@@ -33,8 +33,8 @@ impl DataAcquisitionServiceImpl {
     pub fn new() -> Self {
         Self {
             downloader: Arc::new(DatabentoDownloader::new(DatabentoDownloaderConfig::default())),
-            uploader: Arc::new(MinIOUploader::new(MinIOUploaderConfig::default())),
-            validator: Arc::new(DataValidator::new(ValidationConfig::default())),
+            _uploader: Arc::new(MinIOUploader::new(MinIOUploaderConfig::default())),
+            _validator: Arc::new(DataValidator::new(ValidationConfig::default())),
             job_store: Arc::new(RwLock::new(std::collections::HashMap::new())),
         }
     }
@@ -47,8 +47,8 @@ impl DataAcquisitionServiceImpl {
     ) -> Self {
         Self {
             downloader: Arc::new(DatabentoDownloader::new(downloader_config)),
-            uploader: Arc::new(MinIOUploader::new(uploader_config)),
-            validator: Arc::new(DataValidator::new(validator_config)),
+            _uploader: Arc::new(MinIOUploader::new(uploader_config)),
+            _validator: Arc::new(DataValidator::new(validator_config)),
             job_store: Arc::new(RwLock::new(std::collections::HashMap::new())),
         }
     }
@@ -195,7 +195,7 @@ impl DataAcquisitionService for DataAcquisitionServiceImpl {
         let page = req.page.max(1) as usize;
         let page_size = req.page_size.max(1).min(100) as usize;
         let start_idx = (page - 1) * page_size;
-        let end_idx = start_idx + page_size;
+        let _end_idx = start_idx + page_size;
 
         let total_count = jobs.len() as u32;
         let paginated_jobs = jobs.into_iter().skip(start_idx).take(page_size);

services/data_acquisition_service/src/validator.rs

@@ -59,13 +59,13 @@ pub enum IssueSeverity {
 
 /// Data validator
 pub struct DataValidator {
-    config: ValidationConfig,
+    _config: ValidationConfig,
 }
 
 impl DataValidator {
     /// Create new validator
     pub fn new(config: ValidationConfig) -> Self {
-        Self { config }
+        Self { _config: config }
     }
 
     /// Validate a downloaded file