cosmetic: rename ios-runner -> apple-runner #981

Finish the cosmetic ios-runner → apple-runner rename now that the runner is the OS-agnostic Apple engine (drives iOS/iPadOS/tvOS/macOS/visionOS from one Xcode project).

Scope

• Top-level dir ios-runner/ → apple-runner/ (AgentDeviceRunner/, README.md, RUNNER_PROTOCOL.md).
• Update consumers: scripts/build-xcuitest-apple.sh:92 derived path ($HOME/.agent-device/ios-runner/derived/...), src/platforms/ios/__tests__/recording-scripts.test.ts path (../../../../ios-runner/...), the runtime cache dir, and the files glob + prepack paths in package.json.
• Rename remaining Ios-prefixed runner symbols whose code is now OS-agnostic: runIosRunnerCommand, createIosRunnerCachePrewarmOnColdBoot (src/daemon/handlers/session-state.ts:7). (apple-runner-platform.ts, daemon/apple-runner-options.ts, buildAppleRunnerRequestOptions are already renamed.)

Cosmetic only — no behavior change — but it touches build scripts and cache paths, so verify pnpm build:xcuitest and a live prepare still resolve the derived/cache dirs. Low priority.

Part of #972 (Phase 3 — Apple PlatformPlugin).