feat(FR-433): wrap customTags contents with Collapse

[agatha197]

resolves #3066 (FR-433 / parent: FR-432)

Adds support for reasoning extraction and display in chat messages. This enhances the chat interface by showing AI model's thought process in collapsible sections.

Key changes:

• Added middleware to extract reasoning content from "think" tags
• Implemented collapsible reasoning panels in chat messages
• Added loading state indicator during streaming
• Updated translations for reasoning-related UI text
• Upgraded AI SDK packages to support reasoning extraction

Screenshots:

Checklist:

• Documentation
• Test case(s) to demonstrate the difference of before/after

[agatha197]

Warning

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• feat(FR-433): wrap customTags contents with Collapse #3073 👈 (View in Graphite)
• feat(FR-434): support math in model card. #3067
• main

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