/paste — Clean content for any destination

Cleans terminal output (ANSI, box-drawing, prompt artifacts, etc.) and reformats per destination rules. Reads clipboard by default, writes back to clipboard + previews in chat.

Step 1 — Get the content

In order:

1. If the user included content in the prompt (pasted, or referenced from earlier in the conversation), use that.
2. Else, read clipboard: pbpaste
3. If both empty, ask the user what to paste.

Step 2 — Parse destination