Fix same-origin View run popups

[aronprins]

Summary

• classify Electron new-window requests so same-origin Paperclip routes are navigated in the existing app window
• keep different-origin HTTP(S) links opening in the default browser
• deny unsupported, malformed, and credential-bearing window-policy URLs
• catch failed in-app popup navigation and external browser handoff promises to avoid unhandled rejections from renderer-controlled URLs

Closes #22.

Tests and scans

• pnpm build && node --test test/window-policy.test.mjs
• pnpm test:connections
• pnpm audit --prod
• pnpm audit --dev