feat: optimize document upload process and enhance memory management

- Increased maximum file upload limit from 10 to 50 to improve user experience.
- Implemented batch processing for document uploads to avoid proxy timeouts, splitting files into manageable chunks.
- Enhanced garbage collection in chat streaming functions to prevent memory leaks and improve performance.
- Added memory delta tracking in system snapshots for better monitoring of resource usage.
- Updated LLM router and service configurations to prevent unbounded internal accumulation and improve efficiency.

surfsense_web/components/sources/DocumentUploadTab.tsx

@@ -111,8 +111,8 @@ const FILE_TYPE_CONFIG: Record<string, Record<string, string[]>> = {
 
 const cardClass = "border border-border bg-slate-400/5 dark:bg-white/5";
 
-// Upload limits
-const MAX_FILES = 10;
+// Upload limits — files are sent in batches of 5 to avoid proxy timeouts
+const MAX_FILES = 50;
 const MAX_TOTAL_SIZE_MB = 200;
 const MAX_TOTAL_SIZE_BYTES = MAX_TOTAL_SIZE_MB * 1024 * 1024;