Feature: Slack-style emoji shortcodes in text input

Problem

The Claude Code terminal input runs in raw mode, so system-level emoji tools (like Rocket, macOS text replacements) don't work. The only option is the macOS emoji picker (Ctrl+Cmd+Space), which breaks the flow of typing.

Proposed Solution

Convert :emoji_name: shortcodes to their Unicode emoji when the closing : is typed, similar to how Slack, GitHub, and Discord handle it. Ideally with autocomplete suggestions as you type.

Why

Small quality-of-life improvement — emoji are commonly used in commit messages, PR descriptions, and general communication with Claude. Having inline shortcode support would make the input feel more natural for anyone used to Slack/GitHub workflows.