feat(terminal): right-click send for selected text

[attson]

Summary

Add a 发送 / Send item to the desktop terminal's right-click menu. Sends the current xterm selection back to the same pane's PTY with a trailing \r, executing immediately. Bypasses term.paste() deliberately so bracketed-paste mode doesn't swallow the Enter in zsh / bash / TUIs that have bracketed paste on.

• Selection is C1-stripped (same path as typed input) and every newline shape (\n, \r\n, \r) normalized to a single \r per line, with one final \r appended.
• Enabled iff: non-empty selection AND session attached AND remote_permission != view AND this client is the current driver. Greyed otherwise.
• Two pure helpers (canSendSelection, prepareSendPayload) live in desktop/frontend/src/lib/terminalContextMenu.ts so the SFC stays a thin wrapper.

Spec: docs/superpowers/specs/2026-05-30-terminal-right-click-send-design.md
Plan: docs/superpowers/plans/2026-05-30-terminal-right-click-send.md

Test Plan

• cd desktop/frontend && npx vitest run — 71 files / 607 tests pass
• cd desktop/frontend && npm run build — vue-tsc + vite clean
• In wails dev: select an old command from scrollback → right-click → 发送 → command re-runs
• Multi-line: select two consecutive command lines → 发送 → both run in order, no spurious trailing prompt
• No selection → 发送 is greyed
• remote_permission = view → 发送 is greyed
• Let another client claim driver (overlay shows) → 发送 is greyed
• Switch UI language zh-CN ↔ en → label flips 发送 ↔ send; menu still fits viewport near bottom edge