docs(adr): specify iPhone spatial capture and fusion node

[ruvnet]

Summary

1. Adds ADR 343 for the ten iPhone 17 Pro capabilities requested.
2. Defines the iPhone as a visible spatial capture, calibration, inference, and fusion node.
3. Keeps optical NLOS behind an external transient histogram interface.
4. Selects VL53L8CH as the implementable reference accessory while retaining VL53L8CX as a research reproduction adapter.
5. Specifies public Apple API boundaries, versioned contracts, pseudocode, architecture, security, privacy, rollout, rollback, and acceptance gates.
6. Adds a phased implementation guide and a verification metaharness spanning unit, contract, fuzz, simulator, web, physical device, accessory, and controlled scene testing.

Decision boundary

The built in iPhone LiDAR does not expose the raw transient measurements required by arXiv 2605.17865 through public Apple APIs. This ADR does not claim optical sensing around corners from the phone alone.

The iPhone does not capture WiFi CSI. It consumes authenticated RuView observations and aligns them to a measured room frame.

Bluetooth Channel Sounding, UWB direction, and combined AR products remain runtime gated.

Validation

1. Markdown structure and internal claim scan completed.
2. Primary references are included for the paper, Apple hardware and frameworks, and ST histogram sensor.
3. All numeric performance and accuracy thresholds are marked TARGET until physical evidence exists.
4. Build, simulator, and documentation review do not satisfy physical hardware gates.

Stack

This documentation pull request targets feat/consumer-nlos-ruview and is intentionally separate from mobile UI pull request 1694.

Related to 1687 and 1690.