Add Planar Capture System implementation checklist and developer reference

- Created a comprehensive implementation checklist for the Planar Capture System (Systems 136-147) detailing tasks across multiple phases including C++ core, material foundation, Blueprint actors, data assets, integration, and performance testing.
- Added a developer reference document outlining the architecture, data flow, state machine, budget enforcement, render target pooling, horror features, integration points, multiplayer networking, performance characteristics, debugging methods, and build order for the capture systems.
- Introduced examples of capture surface usage in the Project Void horror game, including specific implementations for mirrors, monitors, portals, and fake windows, along with a checklist for integration tasks.

docs/checklists/cpp-blueprint-status.md

@@ -1,6 +1,6 @@
-# C++ & Blueprint Status Checklist — All 135 Systems
+# C++ & Blueprint Status Checklist — All 147 Systems
 
-**Version:** 2.0 | **Generated:** 2026-05-21 | **C++ Files:** 22 `.h` + 22 `.cpp` (12 full implementations + 10 stubs)
+**Version:** 2.1 | **Generated:** 2026-05-22 | **C++ Files:** 27 `.h` + 27 `.cpp` (15 full implementations + 10 stubs)
 
 Complete status grid for every system in the UE5 Modular Game Framework. Use this to track: which systems have C++ code written, which Blueprint specs are complete, and what Blueprint assets remain to create.
 
@@ -213,6 +213,27 @@ Abbreviations:
 
 ---
 
+## Phase 17: Planar Capture System (17-capture — 12 systems)
+
+### Capture Components & Actors (17-capture)
+
+| # | System | C++ | BP Spec | BP Asset |
+|---|--------|-----|---------|----------|
+| 136 | `BPC_PlanarCapture` | ✅ Full — `Capture/BPC_PlanarCapture` | ✅ | None (use C++ component directly) |
+| 137 | `BP_PlanarCaptureActor` | ✅ Full — `Capture/BP_PlanarCaptureActor` | ✅ | BP children (139-143 extend this) |
+| 138 | `SS_PlanarCaptureManager` | ✅ Full — `Capture/SS_PlanarCaptureManager` | ✅ | None (auto-created WorldSubsystem) |
+| 139 | `BP_Mirror` | 🔵 BP-only | ✅ | BP actor child of BP_PlanarCaptureActor |
+| 140 | `BP_Portal` | 🔵 BP-only | ✅ | BP actor child of BP_PlanarCaptureActor |
+| 141 | `BP_Monitor` | 🔵 BP-only | ✅ | BP actor child of BP_PlanarCaptureActor |
+| 142 | `BP_HorrorMirror` | 🔵 BP-only (extends BP_Mirror) | ✅ | BP actor child of BP_Mirror |
+| 143 | `BP_FakeWindow` | 🔵 BP-only | ✅ | BP actor child of BP_PlanarCaptureActor |
+| 144 | `M_CaptureSurface_Master` | ⬜ Content Asset | ✅ | Create Material in editor |
+| 145 | `MPC_CaptureSurface` | ⬜ Content Asset | ✅ | Create MPC in editor |
+| 146 | `DA_PlanarCaptureProfile` | 🔵 BP-only | ✅ | ⬜ Data Asset instances |
+| 147 | `MI_MirrorInstances` | ⬜ Content Asset | ✅ | 7 Material Instance Constants |
+
+---
+
 ## Quick Action List — What to Build Next
 
 ### Immediate (Phase 0 — Foundation)
@@ -261,7 +282,7 @@ Abbreviations:
 
 ## C++ Source File Index
 
-### Full Implementations (12 systems — logic complete, no BP child needed for functionality)
+### Full Implementations (15 systems — logic complete, no BP child needed for functionality)
 
 | # | C++ Class | Header | Source | Size |
 |---|-----------|--------|--------|------|
@@ -277,6 +298,9 @@ Abbreviations:
 | 72 | `UBPC_DamageReceptionSystem` | `Public/Weapons/BPC_DamageReceptionSystem.h` | `Private/Weapons/BPC_DamageReceptionSystem.cpp` | 150 + cpp |
 | 128 | `USS_EnhancedInputManager` | `Public/Input/SS_EnhancedInputManager.h` | `Private/Input/SS_EnhancedInputManager.cpp` | 232 + cpp |
 | 130 | `UBPC_StateManager` | `Public/Player/BPC_StateManager.h` | `Private/Player/BPC_StateManager.cpp` | 246 + cpp |
+| 136 | `UBPC_PlanarCapture` | `Public/Capture/BPC_PlanarCapture.h` | `Private/Capture/BPC_PlanarCapture.cpp` | 360 + cpp |
+| 137 | `ABP_PlanarCaptureActor` | `Public/Capture/BP_PlanarCaptureActor.h` | `Private/Capture/BP_PlanarCaptureActor.cpp` | 250 + cpp |
+| 138 | `ASS_PlanarCaptureManager` | `Public/Capture/SS_PlanarCaptureManager.h` | `Private/Capture/SS_PlanarCaptureManager.cpp` | 330 + cpp |
 
 ### C++ Stubs (10 systems — UCLASS + basic vars/delegates, need BP child for logic)
 
@@ -293,6 +317,26 @@ Abbreviations:
 | 120 | `UDA_EquipmentConfig` | `Public/Inventory/DA_EquipmentConfig.h` | `Private/Inventory/DA_EquipmentConfig.cpp` | Equipment config stub |
 | 131 | `UDA_StateGatingTable` | `Public/State/DA_StateGatingTable.h` | `Private/State/DA_StateGatingTable.cpp` | Gating table stub |
 
+### Planar Capture Systems (3 full C++ implementations)
+
+| # | C++ Class | Header | Source | Purpose |
+|---|-----------|--------|--------|---------|
+| 136 | `UBPC_PlanarCapture` | `Public/Capture/BPC_PlanarCapture.h` | `Private/Capture/BPC_PlanarCapture.cpp` | SceneCapture2D lifecycle, camera math, horror features |
+| 137 | `ABP_PlanarCaptureActor` | `Public/Capture/BP_PlanarCaptureActor.h` | `Private/Capture/BP_PlanarCaptureActor.cpp` | Placeable surface actor with mesh, MDI, proximity trigger |
+| 138 | `ASS_PlanarCaptureManager` | `Public/Capture/SS_PlanarCaptureManager.h` | `Private/Capture/SS_PlanarCaptureManager.cpp` | Global budget manager, RT pool, surface scoring |
+
+### Capture Utility (Static Library)
+
+| # | C++ Class | Header | Source | Purpose |
+|---|-----------|--------|--------|---------|
+| — | `UPlanarCaptureCameraUtils` | `Public/Capture/PlanarCaptureCameraUtils.h` | `Private/Capture/PlanarCaptureCameraUtils.cpp` | Mirror/portal/oblique projection math |
+
+### Capture Common (Shared Types)
+
+| # | C++ Class | Header | Source | Purpose |
+|---|-----------|--------|--------|---------|
+| — | `PlanarCaptureCommon.h` | `Public/Capture/PlanarCaptureCommon.h` | `Private/Capture/PlanarCaptureCommon.cpp` | Shared enums, structs, quality profiles |
+
 ---
 
-*Status Checklist v2.0 — Updated 2026-05-21. See [`remaining-blueprint-build-order.md`](remaining-blueprint-build-order.md) for the prioritized build list.*
+*Status Checklist v2.1 — Updated 2026-05-22. See [`remaining-blueprint-build-order.md`](remaining-blueprint-build-order.md) for the prioritized build list.*