Control hub 2a: add stable descriptor mapping and deterministic runtime projectors

[EffortlessSteven]

Parent

#301

Dependency

#300 generic control-stream domain contract.

Goal

Convert parsed OpenFlight device-runtime state into stable descriptor/baseline/event/reset items without introducing the multi-subscriber service hub yet.

Scope

• Build a descriptor registry mapping device/runtime numeric IDs to stable external control IDs.
• Preserve raw IDs and semantic provenance when roles are not validated.
• Implement pure/projector logic for initial non-actionable baseline, button press/release, hat direction/neutral, encoder deltas, selected rate-limited axes, and reset/disconnect.
• Integrate projectors with simulated T.Flight and simulated STECS runtime fixtures through narrow adapters.
• Suppress duplicate/unchanged state.
• Preserve deterministic per-device ordering and sequence semantics.
• Keep all network/tonic and subscriber/backpressure logic out of this issue.

Acceptance criteria

• Simulated T.Flight emits descriptor, baseline, button, and hat events.
• Simulated STECS emits descriptor, baseline, representative button, and encoder events.
• Initial/held state never synthesizes a press.
• Duplicate snapshots emit nothing.
• Reset/disconnect clears comparison state.
• Stable/numeric ID mapping and raw/candidate/validated provenance are tested.
• No protected RT path gains blocking, allocation, or network I/O.

Non-goals

• Multi-subscriber event hub/backpressure (Control hub 2b: add the bounded multi-subscriber event hub and gap/reset lifecycle #306).
• gRPC/IPC.
• Runbook bridge.
• Device output.