* feat: add tmux-style double-click copy
Double-clicking terminal output now selects and copies the token under the cursor, similar to tmux. The copied token briefly stays highlighted as feedback, and token detection handles common shell output like paths, URLs, variables, CJK text, and surrounding punctuation.
Mouse events are still forwarded unchanged when the child terminal has mouse reporting enabled.
refs #142
* fix: tighten double-click copy
refs #142
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Co-authored-by: Can Celik <ogulcancelik@gmail.com>