[FEATURE] Add reload/restart session shortcut (similar to VS Code's Reload Window)

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

### Summary

Add a keyboard shortcut or slash command to reload/restart the Claude Code session without having to exit and re-run claude from the terminal.

### Motivation

VS Code has a Reload Window command that restarts the editor in-place without closing the window. This is particularly useful when:

• Configuration files (e.g., settings.json, CLAUDE.md) have been modified and need to take effect
• Installed or updated plugins/skills need to be reloaded

Currently, the only way to reload Claude Code is to type /exit and re-run claude, which interrupts the workflow.

### Expected Behavior

• Session state is cleared (conversation history reset)
• All configuration files (settings.json, CLAUDE.md, skills, etc.) are re-read from disk
• The terminal window/context remains intact (no need to re-navigate to the project directory)

### Current Workaround

```bash
/exit or exit

### Proposed Solution

  One or more of the following:

  1. **Slash command**: `/reload` or `/restart` — restarts the session in-place, re-reading all config files
  2. **Keyboard shortcut**: A configurable keybinding that triggers the same behavior

### Alternative Solutions

_No response_

### Priority

High - Significant impact on productivity

### Feature Category

CLI commands and flags

### Use Case Example

_No response_

### Additional Context

_No response_