Add Sidebar Configuration.user.prompt

# Add Sidebar Configuration Controls

**Agent:** Streamlit UI Development Agent  
**Category:** UI Development  
**Complexity:** Simple  
**Duration:** 30-60 minutes

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## Purpose

Add comprehensive sidebar configuration controls for Claude model selection, parameters, and application settings.

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## Instructions

Create sidebar with:

1. **Model selection dropdown**
2. **Parameter controls** (temperature, max_tokens)
3. **System prompt editor**
4. **Save/reset configuration**
5. **Session state persistence**

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## Expected Output