chore: remove legacy deps (fnntw, rayon) and unused files

- Remove fnntw (KNN) and rayon dependencies, no longer needed with
  ensemble architecture
- Update burn features to include wgpu and train backends
- Remove dev.toml, models/.gitkeep, scripts/convert_csic.py, and
  pingora-headless.yaml (superseded by cluster gossip discovery)
- Add .DS_Store to .gitignore

Signed-off-by: Sienna Meridian Satterwhite <sienna@sunbeam.pt>

Cargo.toml

@@ -38,9 +38,8 @@ opentelemetry-otlp    = { version = "0.27", features = ["http-proto", "reqwest-c
 serde_json = "1"
 anyhow     = "1"
 
-# DDoS detection (KNN classifier)
+# CLI + serialization
 clap        = { version = "4", features = ["derive"] }
-fnntw       = "0.4"
 bincode     = "1"
 rustc-hash  = "2"
 
@@ -77,14 +76,13 @@ iroh-gossip = { version = "0.96", features = ["net"] }
 blake3      = "1"
 hex         = "0.4"
 rand        = "0.9"
-rayon       = "1"
 tempfile    = "3"
 
 # Dataset ingestion (CIC-IDS2017 CSV parsing)
 csv         = "1"
 
 # burn-rs ML framework (training only, behind `training` feature)
-burn = { version = "0.20", features = ["ndarray", "autodiff"], optional = true }
+burn = { version = "0.20", features = ["wgpu", "autodiff", "train"], optional = true }
 
 [features]
 training = ["burn"]