fix terminal corruption that could happen when onboarding and update banner

[nornagon-openai]

Instead of printing characters before booting the app, make the upgrade banner a history cell so it's well-behaved.

[chatgpt-codex-connector]

💡 Codex Review

codex/codex-rs/tui/src/update_prompt.rs

Lines 1 to 4 in c5630e0

	#![cfg(not(debug_assertions))]
	use crate::UpdateAction;
	use crate::history_cell::padded_emoji;

Update prompt imports removed UpdateAction symbol

The move of UpdateAction into the updates module removed the pub enum UpdateAction from the crate root, but update_prompt.rs still does use crate::UpdateAction;. Because the crate root no longer re‑exports this type, release builds (where this module is compiled) will fail to compile with an unresolved import. Import the enum from crate::updates::UpdateAction (or re‑export it) so the update prompt continues to build.

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[joshka-oai]

LGTM - added ratatui-macros to shorten the amount of boilerplate Line::from code, used an existing constant for CODEX_CLI_VERSION