docs(macos-setup): add macOS migration and real iPhone control guide

Documents moving the repo from Windows/other dev machines to macOS and
driving a real iPhone end-to-end via Appium + WebDriverAgent: Xcode/Appium
toolchain setup, WDA signing (using the extra_capabilities passthrough
already supported by WDADriverConfig), minimal real-device verification,
and starting a Runtime API that explicitly registers and connects the
device (neither the Console nor REST API currently expose a
connect/disconnect endpoint). Also covers multi-device port allocation,
common failure modes, and a completion checklist. README gains a pointer
to it under a new "Operator Guides" section.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

README.md

@@ -27,3 +27,9 @@ contracts.
 The durable roadmap is in [docs/ROADMAP.md](docs/ROADMAP.md). The architecture
 invariants future changes must preserve are in
 [docs/CONSTITUTION.md](docs/CONSTITUTION.md).
+
+## Operator Guides
+
+- [macOS migration and real iPhone setup](docs/MACOS_IPHONE_SETUP.md): install
+  Xcode, Appium/XCUITest, sign WebDriverAgent, verify a real device, and start a
+  connected Runtime API.