feat: Training mode, ADR docs, vitals and wifiscan crates

- Add --train CLI flag with dataset loading, graph transformer training,
  cosine-scheduled SGD, PCK/OKS validation, and checkpoint saving
- Refactor main.rs to import training modules from lib.rs instead of
  duplicating mod declarations
- Add ADR-021 (vital sign detection), ADR-022 (Windows WiFi enhanced
  fidelity), ADR-023 (trained DensePose pipeline) documentation
- Add wifi-densepose-vitals crate: breathing, heartrate, anomaly
  detection, preprocessor, and temporal store
- Add wifi-densepose-wifiscan crate: 8-stage signal intelligence
  pipeline with netsh/wlanapi adapters, multi-BSSID registry,
  attention weighting, spatial correlation, and breathing extraction

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

rust-port/wifi-densepose-rs/crates/wifi-densepose-wifiscan/src/port/mod.rs

@@ -0,0 +1,9 @@
+//! Port definitions for the BSSID Acquisition bounded context.
+//!
+//! Hexagonal-architecture ports that abstract the WiFi scanning backend,
+//! enabling Tier 1 (netsh), Tier 2 (wlanapi FFI), and test-double adapters
+//! to be swapped transparently.
+
+mod scan_port;
+
+pub use scan_port::WlanScanPort;

rust-port/wifi-densepose-rs/crates/wifi-densepose-wifiscan/src/port/scan_port.rs

@@ -0,0 +1,17 @@
+//! The primary port (driving side) for WiFi BSSID scanning.
+
+use crate::domain::bssid::BssidObservation;
+use crate::error::WifiScanError;
+
+/// Port that abstracts the platform WiFi scanning backend.
+///
+/// Implementations include:
+/// - [`crate::adapter::NetshBssidScanner`] -- Tier 1, subprocess-based.
+/// - Future: `WlanApiBssidScanner` -- Tier 2, native FFI (feature-gated).
+pub trait WlanScanPort: Send + Sync {
+    /// Perform a scan and return all currently visible BSSIDs.
+    fn scan(&self) -> Result<Vec<BssidObservation>, WifiScanError>;
+
+    /// Return the BSSID to which the adapter is currently connected, if any.
+    fn connected(&self) -> Result<Option<BssidObservation>, WifiScanError>;
+}