feat(train): Add ruvector integration — ADR-016, deps, DynamicPersonMatcher

- docs/adr/ADR-016: Full ruvector integration ADR with verified API details
  from source inspection (github.com/ruvnet/ruvector). Covers mincut,
  attn-mincut, temporal-tensor, solver, and attention at v2.0.4.
- Cargo.toml: Add ruvector-mincut, ruvector-attn-mincut, ruvector-temporal-
  tensor, ruvector-solver, ruvector-attention = "2.0.4" to workspace deps
  and wifi-densepose-train crate deps.
- metrics.rs: Add DynamicPersonMatcher wrapping ruvector_mincut::DynamicMinCut
  for subpolynomial O(n^1.5 log n) multi-frame person tracking; adds
  assignment_mincut() public entry point.
- proof.rs, trainer.rs, model.rs, dataset.rs, subcarrier.rs: Agent
  improvements to full implementations (loss decrease verification, SHA-256
  hash, LCG shuffle, ResNet18 backbone, MmFiDataset, linear interp).
- tests: test_config, test_dataset, test_metrics, test_proof, training_bench
  all added/updated. 100+ tests pass with no-default-features.

https://claude.ai/code/session_01BSBAQJ34SLkiJy4A8SoiL4

rust-port/wifi-densepose-rs/crates/wifi-densepose-train/tests/test_dataset.rs

@@ -5,8 +5,10 @@
 //! directory use [`tempfile::TempDir`].
 
 use wifi_densepose_train::dataset::{
-    CsiDataset, DatasetError, MmFiDataset, SyntheticCsiDataset, SyntheticConfig,
+    CsiDataset, MmFiDataset, SyntheticCsiDataset, SyntheticConfig,
 };
+// DatasetError is re-exported at the crate root from error.rs.
+use wifi_densepose_train::DatasetError;
 
 // ---------------------------------------------------------------------------
 // Helper: default SyntheticConfig
@@ -255,7 +257,7 @@ fn two_datasets_same_config_same_samples() {
 /// shapes (and thus different data).
 #[test]
 fn different_config_produces_different_data() {
-    let mut cfg1 = default_cfg();
+    let cfg1 = default_cfg();
     let mut cfg2 = default_cfg();
     cfg2.num_subcarriers = 28; // different subcarrier count
 
@@ -302,7 +304,7 @@ fn get_large_index_returns_error() {
 // MmFiDataset — directory not found
 // ---------------------------------------------------------------------------
 
-/// [`MmFiDataset::discover`] must return a [`DatasetError::DirectoryNotFound`]
+/// [`MmFiDataset::discover`] must return a [`DatasetError::DataNotFound`]
 /// when the root directory does not exist.
 #[test]
 fn mmfi_dataset_nonexistent_directory_returns_error() {
@@ -322,14 +324,13 @@ fn mmfi_dataset_nonexistent_directory_returns_error() {
         "MmFiDataset::discover must return Err for a non-existent directory"
     );
 
-    // The error must specifically be DirectoryNotFound.
-    match result.unwrap_err() {
-        DatasetError::DirectoryNotFound { .. } => { /* expected */ }
-        other => panic!(
-            "expected DatasetError::DirectoryNotFound, got {:?}",
-            other
-        ),
-    }
+    // The error must specifically be DataNotFound (directory does not exist).
+    // Use .err() to avoid requiring MmFiDataset: Debug.
+    let err = result.err().expect("result must be Err");
+    assert!(
+        matches!(err, DatasetError::DataNotFound { .. }),
+        "expected DatasetError::DataNotFound for a non-existent directory"
+    );
 }
 
 /// An empty temporary directory that exists must not panic — it simply has