fix(adr-017): Add missing cfg(feature = "ruvector") gates to MAT re-exports

Three pub use statements in detection/mod.rs and localization/mod.rs were
re-exporting ruvector-gated symbols unconditionally, and triangulation.rs
had ruvector_solver imports without feature gates. These caused unresolved-
import errors in --no-default-features builds.

- detection/mod.rs: gate CompressedBreathingBuffer + CompressedHeartbeatSpectrogram
- localization/mod.rs: gate solve_tdoa_triangulation
- triangulation.rs: gate use ruvector_solver::*, fn + test module with #[cfg]

All 7 ADR-017 integrations now compile with both default and no-default-features.

https://claude.ai/code/session_01BSBAQJ34SLkiJy4A8SoiL4

rust-port/wifi-densepose-rs/crates/wifi-densepose-mat/src/detection/mod.rs

@@ -12,8 +12,12 @@ mod heartbeat;
 mod movement;
 mod pipeline;
 
-pub use breathing::{BreathingDetector, BreathingDetectorConfig, CompressedBreathingBuffer};
+pub use breathing::{BreathingDetector, BreathingDetectorConfig};
+#[cfg(feature = "ruvector")]
+pub use breathing::CompressedBreathingBuffer;
 pub use ensemble::{EnsembleClassifier, EnsembleConfig, EnsembleResult, SignalConfidences};
-pub use heartbeat::{HeartbeatDetector, HeartbeatDetectorConfig, CompressedHeartbeatSpectrogram};
+pub use heartbeat::{HeartbeatDetector, HeartbeatDetectorConfig};
+#[cfg(feature = "ruvector")]
+pub use heartbeat::CompressedHeartbeatSpectrogram;
 pub use movement::{MovementClassifier, MovementClassifierConfig};
 pub use pipeline::{DetectionPipeline, DetectionConfig, VitalSignsDetector, CsiDataBuffer};