feat: dual-modal WASM browser pose estimation demo (ADR-058)

Live webcam video + WiFi CSI fusion for real-time pose estimation.
Two parallel CNN pipelines (ruvector-cnn-wasm) with attention-weighted
fusion and dynamic confidence gating. Three modes: Dual, Video-only,
CSI-only. Includes pre-built WASM package (~52KB) for browser deployment.

- ADR-058: Dual-modal architecture design
- ui/pose-fusion.html: Main demo page with dark theme UI
- 7 JS modules: video-capture, csi-simulator, cnn-embedder, fusion-engine,
  pose-decoder, canvas-renderer, main orchestrator
- Pre-built ruvector-cnn-wasm WASM package for browser
- CSI heatmap, embedding space visualization, latency metrics
- WebSocket support for live ESP32 CSI data
- Navigation link added to main dashboard

Co-Authored-By: claude-flow <ruv@ruv.net>

ui/index.html

@@ -29,6 +29,7 @@
             <button class="nav-tab" data-tab="applications">Applications</button>
             <button class="nav-tab" data-tab="sensing">Sensing</button>
             <button class="nav-tab" data-tab="training">Training</button>
+            <a href="pose-fusion.html" class="nav-tab" style="text-decoration:none">Pose Fusion</a>
             <a href="observatory.html" class="nav-tab" style="text-decoration:none">Observatory</a>
         </nav>