fix: buffer terminal input before session activation

[jerewy]

Summary

• add a pending input buffer to capture keystrokes before the terminal session becomes ready
• centralize input dispatch logic to reuse filtering and outbound sending across listeners
• flush buffered input once a session id is known and clear buffers on exit to avoid stale replays

Testing

• npm run lint (fails: Failed to load config "next/core-web-vitals" to extend from.)

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https://chatgpt.com/codex/tasks/task_e_68dccf33b8688332a8b41865f17d5165