fix: Fixed code quality issues

[Prekshith-Microsoft]

This pull request includes a variety of improvements and cleanup across the backend, frontend, and documentation. The main themes are backend logic fixes and refactoring, frontend UI and state management cleanup, and documentation corrections. The most important changes are summarized below.

Backend improvements and bug fixes:

• Added an explicit return value when a batch is not found in delete_batch to improve error handling in the batch service (src/backend/common/services/batch_service.py).
• Refactored SQL agent communication and cleanup logic: removed unnecessary destructor for cleanup, clarified return values, and simplified loop control in convert_script.py and comms_manager.py (src/backend/sql_agents/convert_script.py, src/backend/sql_agents/helpers/comms_manager.py). [1] [2] [3] [4]
• Improved error grouping and logging in batch processing and file upload logic (src/backend/common/database/cosmosdb.py, src/backend/common/storage/blob_azure.py, src/backend/api/api_routes.py). [1] [2] [3]
• Refactored C# SQL parsing tool to use LINQ for error list construction (src/backend/sql_agents/tools/src/Program.cs). [1] [2]

Frontend code cleanup and UI improvements:

• Removed unused or redundant state and code in batch history and upload components, and improved error and warning rendering logic (src/frontend/src/components/batchHistoryPanel.tsx, src/frontend/src/components/uploadButton.tsx, src/frontend/src/pages/batchView.tsx). [1] [2] [3] [4] [5] [6] [7] [8] [9] [10]
• Minor fixes to API utility functions and component imports for improved clarity and correctness (src/frontend/src/api/utils.tsx, src/frontend/src/pages/batchView.tsx, src/frontend/src/pages/landingPage.tsx, src/frontend/src/main.jsx, src/frontend/frontend_server.py, src/frontend/src/components/bottomBar.tsx). [1] [2] [3] [4] [5] [6]

Documentation updates:

• Fixed typos, improved link correctness, and clarified deployment instructions in DeploymentGuide.md. [1] [2] [3]## Purpose

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Does this introduce a breaking change?

• Yes
• No

Golden Path Validation

• I have tested the primary workflows (the "golden path") to ensure they function correctly without errors.

Deployment Validation

• I have validated the deployment process successfully and all services are running as expected with this change.

What to Check

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