feat(tui): paste primary selection on middle click

[sshnaidm]

Summary

• Middle click now pastes the X11/Wayland PRIMARY selection into the prompt on Linux, restoring the traditional terminal gesture that was lost when the TUI enables mouse capture
• Adds readPrimary() to the clipboard module (wl-paste → xclip → xsel fallback chain) and exposes it as an optional readPrimary method on ClipboardService
• Registers a hidden prompt.paste.primary command in the prompt and dispatches it from the app root on middle-button mouse down; copy-on-select mouse-up is skipped for middle button so it doesn't clobber the clipboard

Test plan

• bun test in packages/tui (new tests for readPrimaryCommand fallbacks)
• bun typecheck in packages/tui
• Manual: select text with left drag, middle click in prompt area — text is pasted (Linux, X11 and Wayland)

[github-actions]

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[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Potential Duplicate PRs Found

PR #32370: feat(tui): add linux_clipboard_selection config for primary buffer support
#32370

• Directly related to PRIMARY selection handling on Linux; likely addresses the same clipboard/selection functionality

PR #6370: fix: enable primary clipboard copy for Wayland/X11 to fix Linux middle-click paste
#6370

• Addresses X11/Wayland PRIMARY selection for middle-click paste, which is the core feature of PR feat(tui): paste primary selection on middle click #44938

PR #44443: feat(tui): add selection to prompt as quoted context
#44443

• Related to selection handling in the prompt, though likely a different feature

I recommend reviewing PR #32370 and #6370 to ensure PR #44938 doesn't duplicate existing work or conflicts with prior clipboard/selection implementations.

[sshnaidm]

Closing as duplicate of #32370 #6370 #44443
Hopefully one of them will merge 🙏