Fix terminal selection copying

[bifrost0x]

Summary

• copy xterm selections directly through the Clipboard API for Ctrl+C and Cmd+C while preserving Ctrl+C as terminal interrupt input when nothing is selected
• route the Command Palette copy and paste actions through real functions instead of missing DOM buttons
• add unit and browser regression coverage for keyboard and palette copying

Testing

• NODE_PATH=/home/heimdall/Dokumente/ChatGPT/webssh/node_modules node --test tests/js/*.test.js
• eslint static/js/app.js static/js/terminal-manager.js tests/e2e/session-workspace.spec.js tests/js/terminal-manager-layout.test.js
• python -m pytest -q (2,348 passed and 29 skipped in the sandbox; the four socket-bound tests were rerun outside the socket sandbox and passed)
• playwright test tests/e2e/session-workspace.spec.js tests/e2e/profile-launcher.spec.js --forbid-only (35 passed)

Closes #193

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-03T07:47:41.602955Z	c1b70ac	PR opened

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