Feature Request: Persistent chat history with directory isolation

## Feature Description
Add persistent chat history that survives CLI restarts and is isolated by working directory.

## Problem Statement
Currently, when users restart the Amazon Q CLI, all previous chat history is lost. Users cannot use up-arrow navigation to access previous commands from earlier sessions, which reduces productivity and user experience.

## Proposed Solution
Implement persistent chat history with the following features:

### Core Functionality
- **Persistent storage**: Chat history survives CLI restarts using SQLite database
- **Directory isolation**: History for `/project/a` is separate from `/project/b`
- **Up-arrow navigation**: Works seamlessly with persistent history
- **Automatic cleanup**: Maintain max number of entries per directory to prevent unlimited growth

### User Experience
- No configuration required - works out of the box
- Transparent integration with existing readline functionality
- Per-directory isolation matches user mental model

## Use Cases
- Developers working on multiple projects can maintain separate command history
- Long-running development sessions benefit from persistent history across restarts
- Power users with frequent CLI usage get improved productivity