Add synchronized push notification controls

[eivindjonassen]

Summary

• add broker-owned persisted enable and pause state with mobile, CLI, and OpenCode TUI controls
• suppress foreground notification presentation and route permission, form, and session-completion notifications
• preserve notification-owned global-form locations outside followed projects
• harden queued delivery against pause races and document the tested self-hosted setup

Verification

• pnpm check
• pnpm native:doctor (18/18 checks)
• security and correctness pre-commit reviews
• physical iPhone preview-build testing for background, foreground, locked-screen, pause/resume, restart persistence, TUI synchronization, warm/cold permission routing, and global-form routing

Android device verification is deferred.