docs: Add comprehensive wifi-Mat user guide and fix compilation

- Add detailed wifi-Mat user guide covering:
  - Installation and setup
  - Detection capabilities (breathing, heartbeat, movement)
  - Localization system (triangulation, depth estimation)
  - START protocol triage classification
  - Alert system with priority escalation
  - Field deployment guide
  - Hardware setup requirements
  - API reference and troubleshooting

- Update main README.md with wifi-Mat section and links

- Fix compilation issues:
  - Add missing deadline field in AlertPayload
  - Fix type ambiguity in powi calls
  - Resolve borrow checker issues in scan_cycle
  - Export CsiDataBuffer from detection module
  - Add missing imports in test modules

- All 83 tests now passing

rust-port/wifi-densepose-rs/crates/wifi-densepose-mat/src/localization/fusion.rs

@@ -236,11 +236,11 @@ impl PositionFuser {
         let history = self.history.read();
 
         // Use exponentially weighted moving average
-        let alpha = 0.3; // Smoothing factor
+        let alpha: f64 = 0.3; // Smoothing factor
         let mut smoothed = current.position.clone();
 
         for (i, estimate) in history.iter().rev().enumerate().skip(1) {
-            let weight = alpha * (1.0 - alpha).powi(i as i32);
+            let weight = alpha * (1.0_f64 - alpha).powi(i as i32);
             smoothed.x = smoothed.x * (1.0 - weight) + estimate.position.x * weight;
             smoothed.y = smoothed.y * (1.0 - weight) + estimate.position.y * weight;
             smoothed.z = smoothed.z * (1.0 - weight) + estimate.position.z * weight;