🧠 refactor: Improve Reasoning Component Structure and UX (#10320)

* refactor: Reasoning components with independent toggle buttons

- Refactored ThinkingButton to remove unnecessary state and props.
- Updated ContentParts to simplify content rendering and remove hover handling.
- Improved Reasoning component to include independent toggle functionality for each THINK part.
- Adjusted styles for better layout consistency and user experience.

* refactor: isolate hover effects for Reasoning

- Updated ThinkingButton to improve hover effects and layout consistency.
- Refactored Reasoning component to include a new wrapper class for better styling.
- Adjusted icon visibility and transitions for a smoother user experience.

* fix: Prevent rendering of empty messages in Chat component

- Added a check to skip rendering if the message text is only whitespace, improving the user interface by avoiding empty containers.

* chore: Replace div with fragment in Thinking component for cleaner markup

* chore: move Thinking component to Content Parts directory

* refactor: prevent rendering of whitespace-only text in Part component only for edge cases

client/src/components/Chat/Messages/Content/MessageContent.tsx

@@ -4,10 +4,10 @@ import { DelayedRender } from '@librechat/client';
 import type { TMessage } from 'librechat-data-provider';
 import type { TMessageContentProps, TDisplayProps } from '~/common';
 import Error from '~/components/Messages/Content/Error';
-import Thinking from '~/components/Artifacts/Thinking';
 import { useMessageContext } from '~/Providers';
 import MarkdownLite from './MarkdownLite';
 import EditMessage from './EditMessage';
+import Thinking from './Parts/Thinking';
 import { useLocalize } from '~/hooks';
 import Container from './Container';
 import Markdown from './Markdown';