👐 refactor: Agents Accessibility and Gemini Error Handling

[danny-avila]

Summary

Closes #5954

I implemented a series of enhancements across both the server and client components to improve error handling, accessibility, and layout consistency in LibreChat. I improved the GoogleClient’s abort handling and error filtering, replaced outdated dropdowns with the more accessible ControlCombobox, refined focus management in agent selection, and updated UI styling in agent and model panels. I also introduced a new translation key for clearer user copy.

• Updated type annotations and added abort event handling in GoogleClient to catch aborted requests and log warnings for GoogleGenerativeAI errors.

• Improved global error handling in the API server to ignore uncatchable abort errors and log advisory messages for upstream issues.

• Added a selectId prop to AgentSelect and ControlCombobox to maintain focus after agent selection.

• Replaced SelectDropDown components with ControlCombobox in AgentSelect and ModelPanel for better accessibility and consistency.

• Adjusted layout and styling in AgentPanel, AgentPanelSkeleton, and ModelPanel to improve spacing, alignment, and responsiveness.

• Added iconClassName, containerClassName, and iconSide props for enhanced customization in ControlCombobox, AgentSwitcher, and AssistantSwitcher.

• Introduced a new translation key to support improved UI clarity.

• Bug fix (non-breaking change which fixes an issue)

• New feature (non-breaking change which adds functionality)

Testing:

• Manually simulated aborted content generation requests in GoogleClient to verify that abort events are caught and logged.
• Verified in the UI that the new selectId prop keeps focus on the agent selection component after updates.
• Confirmed that layout changes and styling adjustments render correctly across agent panels, skeleton components, and model panels.
• Ensured that the new translation key integrates seamlessly into the UI copy.

Checklist:

• My code adheres to this project's style guidelines
• I have performed a self-review of my own code
• I have commented in any complex areas of my code
• I have made pertinent documentation changes
• My changes do not introduce new warnings
• I have written tests demonstrating that my changes are effective or that my feature works
• Local unit tests pass with my changes
• Any changes dependent on mine have been merged and published in downstream modules