v0.3.7 — Background Unicode input

Keynote can now receive process-targeted Unicode input while another application stays foreground. Use computer_type_text with method: "keyboard" and set both focusPolicy and keyboardPolicy to preserve.

• Verified background Select All and enabled application menu shortcuts.
• Unicode delivery preserves spaces, Chinese text, and emoji without clipboard paste.
• Default Accessibility-first behavior remains available; no automatic resend after an AX success.
• Updated model guidance, English/Chinese docs, and the universal macOS helper.

Validation: 236 unit tests; native background field/shortcut tests; clean Web and Headless package installation; real DSH/Keynote width replacement and subtitle entry with 18,748 continuous foreground samples and no Keynote activation. Background acceptance remains application-dependent.

修复 Keynote 后台文字与数值输入。将两项焦点策略设为 preserve，并明确使用 method: "keyboard"，即可在支持的控件中完成输入，无需抢占前台。已验证真实数值替换、副标题及中英文和 emoji；不支持后台输入的应用仍需单独验证。