Studio chat: show long and invisible-character shell commands faithfully on the approval card #2259

Parent: #2210. Found in the final review of #2251.

Problem

The approval card's shell command view (apps/web/src/features/chat/ask-args-view.tsx) renders the command in a fixed-height scroll box:

• No size hint. A long or multi-line command shows only its first lines above the fold, and nothing tells the reader that more follows. The Edit/Write diff view has a "N more lines" indicator; the command view doesn't.
• Invisible characters render as-is. Bidirectional controls (U+202A–U+202E, U+2066–U+2069) and zero-width characters (U+200B–U+200D, U+FEFF) reach the command, raw and JSON views unchanged. They can make the text a reviewer reads differ from the text that runs.

Expected

A reviewer approving a command can always see all of it, and sees exactly the characters that will run.

Scope

• Show the line count and a "N more lines" affordance when the command overflows, or expand it on demand.
• Render bidi and zero-width characters visibly, e.g. as ⟨U+202E⟩ badges, in the command, raw and JSON views. Consider a warning chip when any are present.
• Tests: a 60-line command shows the overflow indicator; each listed code point renders visibly.