Feat/chat app ai studio refactor

[leehack]

This pull request introduces several updates to the chat app demo, focusing on UI/UX improvements, new model and conversation settings, and codebase organization. The most notable changes include enhancements to theming and layout, expanded configuration options for chat models, and the addition of a new ChatConversation model. Below are the most important changes grouped by theme:

UI/UX Improvements:

• Updated the main app theme in main.dart to use new color schemes, switched to the Manrope font, set dark mode as default, and replaced the home screen with AppShellScreen for a more modern look and feel. [1] [2]
• Refactored ChatScreen to simplify the layout: removed the custom app bar, adjusted background gradients and widget positioning, and improved scroll behavior for smoother user experience. [1] [2] [3] [4] [5] [6]
• Added a link to the chat app demo in the README.md.

Model and Conversation Configuration:

• Expanded ChatSettings and ModelPreset to support additional parameters such as minP, penalty, numberOfThreads, numberOfThreadsBatch, thinkingEnabled, thinkingBudgetTokens, and singleTurnMode, allowing for more granular control of model behavior. [1] [2] [3] [4] [5] [6] [7]

Codebase Organization:

• Introduced a new ChatConversation model to encapsulate conversation state, including messages, settings, and metadata.
• Cleaned up imports and improved navigation logic in chat_screen.dart, including support for custom model selection callbacks and navigation to a new ManageModelsScreen. [1] [2] [3]

These changes collectively improve the flexibility, maintainability, and user experience of the chat app demo.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.37%. Comparing base (3cd126f) to head (0898768).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #58   +/-   ##
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  Coverage   76.37%   76.37%           
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  Files          65       65           
  Lines        7915     7915           
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  Hits         6045     6045           
  Misses       1870     1870           

Flag	Coverage Δ
unittests	76.37% <ø> (ø)

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