[codex] Fix terminal cursor preference handling

[binaricat]

Summary

• keep the terminal cursor following the user's configured shape/blink preference even if terminal output tries to change it
• restore focus to the active terminal after closing the SFTP text editor modal
• add coverage for cursor preference handling and terminal refocus behavior

Context

Issue #833 is difficult to reproduce consistently. This change does not claim a confirmed reproduction; it adds defensive fixes based on the reported symptoms: focused terminal with non-blinking cursor, and input trouble after SFTP editing flows.

Validation

• npm test -- components/terminal/runtime/cursorPreference.test.ts components/terminal/focusTerminalSession.test.ts
• npm run lint
• npm run build
• git diff --check