Copy button missing on code blocks (web UI has it) #4

What happens: in the Android app every fenced code block renders as a read-only box with no copy affordance. In the opencode web client the same session, same message, shows a copy icon in the top-right corner of the block.

Expected: an icon on the code block that copies its contents to the clipboard (same as the web client). Long-press currently gives "Copy message", i.e. the whole message, not the block.

Steps to reproduce: open a session where an assistant reply contains a fenced code block. In the app the block is display-only; in the web client on the same server the copy icon is present.

Why it matters: copying a snippet means selecting the whole message and trimming it by hand, so I fall back to the browser whenever code is involved.

Screenshots

1. Native app — no copy button on the block

2. Web UI, same session — copy button in the top-right corner (highlighted)