chore(release): wifi-densepose-train 0.3.0 -> 0.3.1

Publishing the additive changes from PRs #536/#537 to crates.io:
- `signal_features` module — wires `wifi-densepose-signal` into the pipeline
  (audit #1/#2)
- `TrainingConfig::for_subcarriers` / `ht40_192()` / `multiband_168()` presets
  + the real `MmFiDataset` loader integration test (audit #4/#6/#7)

No public API removals or changes — additive only, so 0.3.0 -> 0.3.1 is
semver-correct. No other workspace crate depends on `wifi-densepose-train`,
so this is a standalone bump.

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

v2/crates/wifi-densepose-train/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "wifi-densepose-train"
-version = "0.3.0"
+version = "0.3.1"
 edition = "2021"
 authors = ["rUv <ruv@ruv.net>", "WiFi-DensePose Contributors"]
 license = "MIT OR Apache-2.0"