feat(chat): add chat detail visibility selector

[lc6464]

📝 Description

Replace the Web Chat assistant detail toggle with a four-state selector for reasoning and tool call visibility.

This PR updates the chat header control to support showing neither, reasoning only, tool calls only, or both. It also migrates the stored browser preference from the legacy boolean key to a new enum-based key and keeps the migration resilient when storage access is restricted.

🗣️ Type of Change

• 🐞 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 📖 Documentation update
• ⚡ Code refactoring (no functional changes, no api changes)

🤖 AI Code Generation

• 🤖 Fully AI-generated (100% AI, 0% Human)
• 🛠️ Mostly AI-generated (AI draft, Human verified/modified)
• 👨‍💻 Mostly Human-written (Human lead, AI assisted or none)

📚 Technical Context

• Reference URL: N/A
• Reasoning: Replace the binary assistant detail toggle with a selector that matches the four supported visibility modes, preserve existing user preference data through localStorage migration, and fall back safely to all when browser storage is unavailable or write-restricted.

🧪 Test Environment

• Hardware: Local x64 Server
• OS: Ubuntu Server 24
• Model/Provider: -
• Channels: Web

📸 Evidence

Click to view Logs/Screenshots

Select, Chinese:

Tool calls only, English:

☑️ Checklist

• My code/docs follow the style of this project.
• I have performed a self-review of my own changes.
• I have updated the documentation accordingly.

[lxowalle]

Please resolve the code conflict

[lc6464]

Please resolve the code conflict

@lxowalle Conflicts have been resolved.

Please review again, thanks!

[lxowalle]

LGTM