Implement Media Capture API

[General-Fault]

Implement full Media Capture and Streams API (MediaStream, MediaStreamTrack, MediaDevices, constraints, DTOs).

Scope

• Include: Full Media Capture API surface including MediaStream, MediaStreamTrack, MediaDevices, all constraint types, and related DTOs
• Exclude: WebRTC API (RtcPeerConnection, RtcRtpSender, etc.), full VideoRenderer implementation
• Platform: Windows only (C++/CLI)

Implementation Order (Dependency Chain)

1. DTO & enum marshalling + EnumerateDevices (Phase 1: Implement MediaDeviceInfo marshalling & EnumerateDevices #49)
2. Constraint type marshalling (Phase 2: Implement MediaTrackCapabilities, MediaTrackSettings, & constraint marshalling #50)
3. GetUserMedia with full constraint handling (Phase 3: Implement GetUserMedia with full constraint handling #51)
4. MediaStreamTrack constraint methods (Phase 4: Implement MediaStreamTrack constraint methods #52)
5. Complete MediaStream & MediaStreamTrack interop (Phase 5: Complete MediaStream & MediaStreamTrack interop #53)

Key Design Decisions

• Use existing marshalling patterns from MarshalIceServer.h, MarshalMediaConstraints.h as templates
• Leverage C++ smart pointers (unique_ptr, shared_ptr, scoped_refptr, ManagedScopedRefPtr)
• Follow copy/move semantics for efficiency
• All constraint marshalling in dedicated header (single responsibility)
• DTOs are pure managed records — marshalling converts native → managed, no round-trip
• Enums use MarshalEnums.h pattern (switch or bidirectional map)

Child Issues

• Phase 1: Implement MediaDeviceInfo marshalling & EnumerateDevices #49: Phase 1 - DTO & enum marshalling + EnumerateDevices
• Phase 2: Implement MediaTrackCapabilities, MediaTrackSettings, & constraint marshalling #50: Phase 2 - Constraint type marshalling
• Phase 3: Implement GetUserMedia with full constraint handling #51: Phase 3 - GetUserMedia with full constraint handling
• Phase 4: Implement MediaStreamTrack constraint methods #52: Phase 4 - MediaStreamTrack constraint methods
• Phase 5: Complete MediaStream & MediaStreamTrack interop #53: Phase 5 - Complete MediaStream & MediaStreamTrack interop

Branch

All work on: feature/48-implement-media-capture-api