Phase 1d: Move connect/disconnect onto Peripheral; demote manager connect

[itsniper]

Parent: #50

Requirements

• Primary connect/disconnect APIs on Peripheral (including autoReconnect Bool on connect).
• ReliaBLEManager.connect(to:) removed, deprecated, or Advanced/internal only—documented.
• Connection state observation usable from handle-centric flow (stream on handle and/or existing manager streams keyed by id—planning chooses).
• Demo uses handle APIs.

Acceptance criteria

• App can connect/disconnect via Peripheral without manager-primary connect
• Existing reconnect/restore behavior preserved at link layer
• Docs/Demo updated