Incorporates Loader state UI during LLM processing

[chrisr0892]

Description

• Added Loader component with MUI CircularProgress.
• LoaderStore added to Zustand Stores.
• Loader added to UserInputForm
• Loader added to OutputVisualizationPage with zustand state to allow for re-rendering when regenerate is clicked.

Fixes #78

Type of change

• [x] ✨ New feature (non-breaking change which adds functionality)

How Can this be tested? Testing Plan to review this PR

• [x] Where in the app does this change take place?
  • UserInputForm.tsx and OutputVisualizationPage.tsx
• [x] What are the steps to test this change?
  • From the /generate route:
  • Enter input and click the Generate button to create a new LinktaFlow.
  • From the side nav:
  • Click the ••• icon and select Regenerate.
• [x] What is the expected output?
  • An animated circular loader will appear in the center of the screen until LLM processing is finished.

    Checklist:

• [x] I have performed a self-review of my own code.
• [ ] I have commented on my code, particularly in hard-to-understand areas.
• [ ] I have made corresponding changes to the documentation.
• [x] My changes generate no new warnings.
• [x] Any dependent changes have been merged and published in downstream modules.
• [x] I have reviewed the Security Best Practices Document.
• [x] I have followed the Naming Conventions Guide for my changes.
• [x] I have ensured that my pull request title is descriptive.

Additional Information:

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[chrisr0892]

Thanks for the good work!

There's a Loader component in /components/common, consider moving the loading functionality from the UserInputForm to this Loader component. Since multiple parts of the app use the Loader, we should make sure this loader is reusable and comprehensive for generic use and add a bit more for LLM interactions.

Currently, the LLM loader is needed in 2 areas so please make sure you incorporate the loader in the respective components.

• UserInputForm
• OptionsMenu (regenerate function)

For LLM interactions, it'd be great to show additional info to reassure users that the process might take a while due to AI processing. Not a requirement and only if you have the capacity, adding a button for the user to cancel the query could help improve our UX too.

For styling, if we are making a reusable loader, prioritize using a CSS object over inline styling if time allows.

Thanks for the review! I moved the loader to existing Loader.tsx component so that it can be reusable and incorporated it in UserInputForm and OutputVisualizationPage (regenerate).