feat: add UE5 LED display client — backend API, C++ source, stereo framework

Backend:
- Add /api/v1/ue/* endpoints (compute-points, cables, landing-points, satellites, status)
  returning flat JSON optimised for UE5 C++ parsing

UE5 client (ue_client/):
- PlanetDataManager: HTTP fetch + local mock JSON loader, spawns ComputePointActors
- ComputePointActor / InteractiveObjectBase: hover/select state, material switching
- GlobeInteractionComponent: drag-to-rotate via CesiumGeoreference origin shift, inertia, zoom
- StereoRenderingManager: runtime SbS/TbB stereo toggle, IPD control (format TBD)
- MotionCaptureInterface: protocol-agnostic gesture/rotate/zoom delegate interface (impl TBD)
- PlanetPlayerController: unified mouse + motion-capture input routing
- PlanetGameMode, Build.cs, Config, mock data

Docs:
- ue5_mvp_fused_plan.md updated to v3.0 for LED display context
- ue_client_setup_guide.md: step-by-step editor setup guide
- ue_todo.md: pending items blocked on vendor answers (stereo format + mocap protocol)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ue_client/Content/Data/mock_compute_points.json

@@ -0,0 +1,135 @@
+{
+  "count": 10,
+  "items": [
+    {
+      "id": "top500_1",
+      "name": "Frontier",
+      "latitude": 36.01,
+      "longitude": -84.26,
+      "country": "United States",
+      "city": "Oak Ridge",
+      "rank": 1,
+      "rmax_tflops": 1194000.0,
+      "rpeak_tflops": 1679616.0,
+      "cores": 8730112,
+      "power_kw": 22703.0
+    },
+    {
+      "id": "top500_2",
+      "name": "Aurora",
+      "latitude": 41.71,
+      "longitude": -87.98,
+      "country": "United States",
+      "city": "Lemont",
+      "rank": 2,
+      "rmax_tflops": 1012000.0,
+      "rpeak_tflops": 1321000.0,
+      "cores": 9264128,
+      "power_kw": 38698.0
+    },
+    {
+      "id": "top500_3",
+      "name": "Eagle",
+      "latitude": 52.36,
+      "longitude": 4.90,
+      "country": "Netherlands",
+      "city": "Amsterdam",
+      "rank": 3,
+      "rmax_tflops": 561200.0,
+      "rpeak_tflops": 736000.0,
+      "cores": 4620800,
+      "power_kw": 12410.0
+    },
+    {
+      "id": "top500_4",
+      "name": "Fugaku",
+      "latitude": 34.66,
+      "longitude": 135.22,
+      "country": "Japan",
+      "city": "Kobe",
+      "rank": 4,
+      "rmax_tflops": 442010.0,
+      "rpeak_tflops": 537212.0,
+      "cores": 7630848,
+      "power_kw": 29899.0
+    },
+    {
+      "id": "top500_5",
+      "name": "LUMI",
+      "latitude": 65.01,
+      "longitude": 25.46,
+      "country": "Finland",
+      "city": "Kajaani",
+      "rank": 5,
+      "rmax_tflops": 379700.0,
+      "rpeak_tflops": 531000.0,
+      "cores": 2748384,
+      "power_kw": 6016.0
+    },
+    {
+      "id": "top500_6",
+      "name": "MareNostrum 5",
+      "latitude": 41.39,
+      "longitude": 2.11,
+      "country": "Spain",
+      "city": "Barcelona",
+      "rank": 6,
+      "rmax_tflops": 138200.0,
+      "rpeak_tflops": 314000.0,
+      "cores": 2764800,
+      "power_kw": 10000.0
+    },
+    {
+      "id": "top500_7",
+      "name": "Summit",
+      "latitude": 35.93,
+      "longitude": -84.31,
+      "country": "United States",
+      "city": "Oak Ridge",
+      "rank": 7,
+      "rmax_tflops": 148600.0,
+      "rpeak_tflops": 200795.0,
+      "cores": 2414592,
+      "power_kw": 10096.0
+    },
+    {
+      "id": "top500_8",
+      "name": "Tianhe-2A",
+      "latitude": 23.13,
+      "longitude": 113.27,
+      "country": "China",
+      "city": "Guangzhou",
+      "rank": 8,
+      "rmax_tflops": 100679.0,
+      "rpeak_tflops": 100679.0,
+      "cores": 4981760,
+      "power_kw": 18482.0
+    },
+    {
+      "id": "top500_9",
+      "name": "Selene",
+      "latitude": 40.82,
+      "longitude": -74.17,
+      "country": "United States",
+      "city": "Santa Clara",
+      "rank": 9,
+      "rmax_tflops": 63460.0,
+      "rpeak_tflops": 79200.0,
+      "cores": 555520,
+      "power_kw": 2646.0
+    },
+    {
+      "id": "top500_10",
+      "name": "Perlmutter",
+      "latitude": 37.88,
+      "longitude": -122.25,
+      "country": "United States",
+      "city": "Berkeley",
+      "rank": 10,
+      "rmax_tflops": 93750.0,
+      "rpeak_tflops": 120000.0,
+      "cores": 761856,
+      "power_kw": 3060.0
+    }
+  ]
+}