feat: add command history persistence (#152)

This PR adds a command history persistence feature to Codex CLI that:

1. **Stores command history**: Commands are saved to
`~/.codex/history.json` and persist between CLI sessions.
2. **Navigates history**: Users can use the up/down arrow keys to
navigate through command history, similar to a traditional shell.
3. **Filters sensitive data**: Built-in regex patterns prevent commands
containing API keys, passwords, or tokens from being saved.
4. **Configurable**: Added configuration options for history size,
enabling/disabling history, and custom regex patterns for sensitive
content.
5. **New command**: Added `/clearhistory` command to clear command
history.

  ## Code Changes

- Added `src/utils/storage/command-history.ts` with functions for
history management
  - Extended config system to support history settings
  - Updated terminal input components to use persistent history
  - Added help text for the new `/clearhistory` command
  - Added CLAUDE.md file for guidance when working with the codebase

  ## Testing

  - All tests are passing
- Core functionality works with both input components (standard and
multiline)
- History navigation behaves correctly at line boundaries with the
multiline editor

codex-cli/src/components/help-overlay.tsx

@@ -49,6 +49,9 @@ export default function HelpOverlay({
         <Text>
           <Text color="cyan">/clear</Text> – clear screen &amp; context
         </Text>
+        <Text>
+          <Text color="cyan">/clearhistory</Text> – clear command history
+        </Text>
 
         <Box marginTop={1}>
           <Text bold dimColor>