Implement Notifications API with Permission Flow

Proposal

Add Notifications support with explicit permission handling and injected delivery backend.

Scope:

• Expose Notification constructor and static requestPermission.
• Support permission states default, granted, denied.
• Add close and basic event wiring.
  Technical Notes:
• Permission and delivery must be platform-injected.
• Integrate with Permissions API when available.
  Acceptance Criteria:
• Notification creation is blocked when permission is denied.
• requestPermission resolves through injected platform policy.
• Unit tests cover permission transitions and delivery callback invocation.
  Out of Scope:
• Native OS notification UI behavior.
• Browser-specific anti-abuse policies.

Description

Implement Notifications API basics, including Notification construction, requestPermission, and permission-state enforcement through an injected platform permission/delivery backend.

Background

Notification support is frequently needed for app parity and user-flow simulation. A platform-injected model aligns with existing Clipboard/Geolocation patterns and keeps host behavior configurable.

Specification

• Notifications specification: https://notifications.spec.whatwg.org/
• Permission model integration expected with Permissions API semantics

Start by examining the existing Clipboard and Geolocation patterns, then trace how Permissions API semantics can be represented through injected platform permission and delivery backends. Map the constructor, requestPermission, permission states, close, events, and delivery callback to the acceptance criteria; done when unit tests cover permission transitions and callback invocation.