Release Scientific Illustrator 1.5.1 background focus fix

[icebird1998]

What changed

• add powerpoint_set_focus_policy with safe preserve default and opt-in foreground mode
• stop ordinary Windows PowerPoint COM mutations from calling window activation
• use background open -g refresh for Mac PowerPoint OOXML and Mac WPS
• use no-activate launch plus foreground restoration for Windows WPS/OOXML
• keep powerpoint_activate_slide as the explicit foreground handoff
• bump the plugin, MCP servers, and Office.js manifest to 1.5.1
• document the behavior and add cross-platform focus-policy regression coverage

Why

The previous presentation backends foregrounded PowerPoint or WPS after individual drawing operations. On Mac OOXML this came from repeated open -a refreshes; on Windows COM it came from ActiveWindow.Activate(). Users could not continue working in other applications while a long reconstruction ran.

Impact

Presentation drawing now keeps the user's current application focused by default. Users who want to watch every step can explicitly switch to foreground. draw.io continues to use its graph/CDP channel and does not repeatedly take focus after launch.

Validation

• full repository and MCP smoke suite passed
• 33 PowerPoint tools discovered, including the new focus-policy tool
• Office.js HTTPS bridge smoke tests passed
• new focus-policy regression suite passed
• Mac PowerPoint real-app check kept ChatGPT frontmost before launch, after background launch, and after an object mutation

Windows PowerPoint/WPS code paths are covered by protocol/static regression checks; a final physical Windows/WPS smoke test is still recommended.