spec: add SPEC-011 Mobile Agent Support (iOS and Android)

Comprehensive specification for iOS/Android devices as remote control targets:

iOS Agent (View-Only):
- ReplayKit 2 screen capture (user consent required)
- VideoToolbox H.264 encoding
- NO input injection (iOS sandboxing limitation)
- APNs push notifications for session requests
- Foreground-only operation (OS requirement)

Android Agent (View + Control):
- MediaProjection API screen capture (user consent)
- MediaCodec H.264 encoding
- Accessibility Service for input injection (tap/swipe/type)
- FCM push notifications
- Foreground service with persistent notification

Architecture:
- Native Swift/SwiftUI (iOS) and Kotlin/Jetpack Compose (Android) apps
- Same protobuf-over-WSS protocol as desktop agents
- Support-code authentication (persistent mode deferred to Phase 2)
- Minor protobuf additions: MobileCapabilities, TouchEvent
- Server push module: APNs (a2 crate) + FCM HTTP v1

Key constraints:
- Attended-only sessions (user must grant permission)
- Foreground-only (cannot capture in background on either platform)
- iOS view-only (platform sandbox prevents input injection)
- Consent-first model (MediaProjection/ReplayKit user prompts)

Estimated effort: X-Large (16-20 weeks, requires mobile expertise)
Priority: P3

Distinct from GuruRMM SPEC-017 (MDM/inventory) — this is remote
control, not device management.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

docs/FEATURE_ROADMAP.md

@@ -94,4 +94,5 @@ Bringing GC to parity with GuruRMM's release engineering. Full plan: [SPEC-001](
 ## Future Considerations
 
 - [ ] **Cross-platform agent support (macOS and Linux)** — P2 — Enable remote control beyond Windows with native agents for macOS 12+ and Ubuntu 22.04+ LTS. Platform abstraction layer for capture/input/encoding, VideoToolbox (macOS) and VA-API (Linux) H.264 encoding, .app/.deb/.rpm packaging. Unblocks multi-platform MSP adoption. ([SPEC-010](specs/SPEC-010-cross-platform-agents.md))
+- [ ] **Mobile agent support (iOS and Android as remote control targets)** — P3 — Native mobile apps for supervised support sessions. iOS: ReplayKit screen sharing (view-only, no input injection due to sandboxing). Android: MediaProjection screen capture + Accessibility Service input injection. Support-code authentication, push notifications (APNs/FCM), consent-first model. Foreground-only operation (OS limitation). Distinct from GuruRMM SPEC-017 (MDM/management). ([SPEC-011](specs/SPEC-011-mobile-agents.md))
 - [ ] Auto-update for the agent — P3