[UX] CLI code blocks have no copy-to-clipboard shortcut

[sprmn24]

Summary

When Hermes renders a code block in the CLI/TUI, there is no way to copy
the code without manually selecting text with the mouse. Tools like Claude
and GitHub show a copy button next to code blocks for quick access.

Repro context

Ask Hermes to write any code snippet in the CLI:

Code block appears in the response with no copy option.

Expected behavior

• A visible [Copy] indicator next to code blocks
• Or a keyboard shortcut (e.g. y) to copy the nearest code block
• Code is copied to system clipboard automatically

Actual behavior

• No copy button or shortcut exists
• User must manually select text with the mouse

Notes

hermes_cli/clipboard.py already provides clipboard infrastructure
for WSL2, Linux (xclip/wl-paste), and macOS. This could be reused
to copy code block text.

Suggested direction

• Detect code blocks in rendered output
• Add a keyboard shortcut or inline [Copy] prompt
• Use existing clipboard.py for cross-platform clipboard support

Workaround

Manually select the code with the mouse and copy.