[FEATURE] One-click copy for inline code in chat (desktop/web), configurable

Summary

Add a one-click copy affordance for inline code spans (`code` fragments inside messages) in the desktop and web UIs — not just fenced code blocks.

Motivation

Inline code shows up constantly in conversations: command names, flags, file paths, identifiers, short snippets. Copying one today requires precise text selection with the mouse, which is slow and error-prone (it's easy to grab surrounding whitespace or punctuation).

Other AI platforms already ship this exact UX — for example, z.ai copies an inline code span on click and gives brief visual feedback. It's a small interaction that removes a lot of day-to-day friction.

Proposed behavior

• Hovering an inline code span shows a pointer cursor plus a subtle affordance (e.g., dashed outline).
• Clicking it copies its text content to the clipboard and shows brief visual feedback (outline flash or toast).
• Guardrails so normal interactions keep working:
  • Don't hijack the click when the user has an active text selection.
  • Don't apply inside fenced code blocks (pre code), links (a code), or diff/hunk views, where click/selection semantics already mean something else.

Configurable

Expose a setting so users can tune or disable it, e.g.:

{
  "ui": {
    "inline_code_click_to_copy": true,
    "inline_code_copy_feedback": "flash"
  }
}

("flash" | "toast" | "none")

Related issues

• #29913 — Allow copying code or file changes from the desktop app conversation history
• #30467 — Copy directly from diff text windows in opencode desktop
• #7696 — Message actions on AI messages (copy button etc.)
• #5641 — Add copy to clipboard functionality for outputted snippets of code

Those cover code blocks, diffs, and message-level actions; this request is specifically about inline spans within prose.

Environment

• OpenCode Desktop (Electron) on Windows 11
• Same behavior would apply to the web UI