fix: Clean up Rust warnings and add Python vital signs detection

Rust changes:
- Fix unused variable warnings in wifi-densepose-nn (densepose.rs, inference.rs, tensor.rs, translator.rs)
- Remove unused imports in wifi-densepose-mat (breathing.rs, pipeline.rs, csi_receiver.rs, debris_model.rs, vital_signs_classifier.rs)
- All tests continue to pass

Python changes:
- Add vital_signs.py module with BreathingDetector and HeartbeatDetector classes
- Mirror Rust wifi-densepose-mat detection functionality
- Update v1 package version to 1.2.0
- Export new vital signs classes from core module

rust-port/wifi-densepose-rs/crates/wifi-densepose-mat/src/integration/csi_receiver.rs

@@ -28,8 +28,6 @@ use chrono::{DateTime, Utc};
 use std::collections::VecDeque;
 use std::io::{BufReader, Read};
 use std::path::Path;
-use std::sync::Arc;
-use tokio::sync::{mpsc, Mutex};
 
 /// Configuration for CSI receivers
 #[derive(Debug, Clone)]