feat: add resume functionality for CLI sessions across backends

[ileixe]

Hi, I want to use codex resume so added the feature. Please take a look.

[Copilot]

Pull Request Overview

This PR adds resume functionality for CLI sessions across backends, allowing users to continue previously started AI CLI sessions. The feature is implemented with backend-specific support and provides a unified interface through the codex resume command.

• Adds a new ai-code-cli-resume command with backend-specific resume implementations
• Updates the AI Code Commands menu to include a "Resume AI CLI" option
• Implements resume support for codex backend with proper session restoration

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
ai-code-interface.el	Adds "Resume AI CLI" menu item to the AI Code Commands interface
ai-code-codex-cli.el	Implements codex-cli-resume function for the codex backend with session restoration
ai-code-backends.el	Adds resume functionality infrastructure with backend configuration and fallback handling

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[Copilot]

The goto-char (point-min) call will move to the beginning of the current buffer, but after calling claude-code--start with force-switch-to-buffer set to t, the current buffer may not be the terminal buffer. This could result in moving the cursor in an unrelated buffer instead of the CLI session buffer.

Suggested change

	(goto-char (point-min))))
	(with-current-buffer claude-code-terminal-backend
	(goto-char (point-min))))))

[tninja]

@ileixe let me know if this AI suggested buffer specification make sense

[ileixe]

Yes, it makes sense. Changed

[Copilot]

The variable shadowing (let ((resume resume))) is unnecessary and confusing. The outer resume variable is already lexically scoped and can be used directly in the lambda closure without this redundant binding.

Suggested change

	(let ((resume resume))
	(fset 'ai-code-cli-resume
	(lambda (&optional arg)
	(interactive "P")
	(let ((current-prefix-arg arg))
	(call-interactively resume)))))
	(fset 'ai-code-cli-resume
	(lambda (&optional arg)
	(interactive "P")
	(let ((current-prefix-arg arg))
	(call-interactively resume))))

[tninja]

@ileixe should we remove this let binding?

[ileixe]

Removed.

[tninja]

Thanks @ileixe for the contribution! It is useful feature. Would you mind help take a look at the review feedback and see if it make sense?

[ileixe]

Thanks @ileixe for the contribution! It is useful feature. Would you mind help take a look at the review feedback and see if it make sense?

Thanks for review. Updated.