Phase 1b: Handle registry, known-id peripheral(id:), and discovery binding

[itsniper]

Parent: #50

Requirements

• Manager (actor) intern registry: one Peripheral handle per id per manager.
• manager.peripheral(id:) creates or returns handle before any advertisement.
• Discovery matching binds live CBPeripheral to existing handle when ids align (and creates handle if none).
• Option A: update handle last-seen / rssi / last-advertisement metadata when discovered.
• No fake DiscoveredPeripheral for offline known ids.

Acceptance criteria

• Known-id handle survives until matched; no duplicate handles for same id
• Metadata on handle updates when nearby
• Tests for known-id + later discovery bind