feat: add hook config support

[PeterCardenas]

Closes #144

Add support for specifying hookConfigs when creating a session to react to hook events.

Hooks are specified with the following type:

export type HookConfig = {
  /** The hook event to listen for */
  event: HookEvent;
  /** 
   * Optional matcher string to filter which tools trigger this hook.
   * Only relevant for tool-related hooks: PreToolUse, PostToolUse, PostToolUseFailure, PermissionRequest
   */
  matcher?: string;
  /** Command to execute */
  command: string;
  /** Arguments for the command */
  args?: string[];
  /** Environment variables to pass to the command */
  env?: Record<string, string>;
};

These commands are executed with environment variables populated with the tool input, so arguments or the command itself can handle the input accordingly.
To give hook output, the command must print, and only print, a JSON string to stdout which will be parsed to use as the hook result. Otherwise, the agent will continue.

[cla-bot]

We require contributors to sign our Contributor License Agreement, and we don't have @PeterCardenas on file. You can sign our CLA at https://zed.dev/cla. Once you've signed, post a comment here that says '@cla-bot check'.

[PeterCardenas]

@cla-bot check

[cla-bot]

The cla-bot has been summoned, and re-checked this pull request!

[AlephNotation]

Checking in on this. It would be nice to support some of the popular tools that use hooks