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/triangulation.rs

@@ -337,11 +337,11 @@ mod tests {
         let sensors = create_test_sensors();
 
         // Target at (5, 4) - calculate distances
-        let target = (5.0, 4.0);
+        let target: (f64, f64) = (5.0, 4.0);
         let distances: Vec<(&str, f64)> = vec![
-            ("s1", ((target.0 - 0.0).powi(2) + (target.1 - 0.0).powi(2)).sqrt()),
-            ("s2", ((target.0 - 10.0).powi(2) + (target.1 - 0.0).powi(2)).sqrt()),
-            ("s3", ((target.0 - 5.0).powi(2) + (target.1 - 10.0).powi(2)).sqrt()),
+            ("s1", ((target.0 - 0.0_f64).powi(2) + (target.1 - 0.0_f64).powi(2)).sqrt()),
+            ("s2", ((target.0 - 10.0_f64).powi(2) + (target.1 - 0.0_f64).powi(2)).sqrt()),
+            ("s3", ((target.0 - 5.0_f64).powi(2) + (target.1 - 10.0_f64).powi(2)).sqrt()),
         ];
 
         let dist_vec: Vec<(SensorPosition, f64)> = distances