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-nn/src/inference.rs

@@ -206,7 +206,7 @@ impl Backend for MockBackend {
         self.output_shapes.get(name).cloned()
     }
 
-    fn run(&self, inputs: HashMap<String, Tensor>) -> NnResult<HashMap<String, Tensor>> {
+    fn run(&self, _inputs: HashMap<String, Tensor>) -> NnResult<HashMap<String, Tensor>> {
         let mut outputs = HashMap::new();
 
         for (name, shape) in &self.output_shapes {