feat(sensing-server): ADR-084 Pass 3.5 — novelty_score on PerNodeFeatureInfo

Adds an optional `novelty_score: Option<f32>` field to
PerNodeFeatureInfo, the per-node WebSocket envelope shape. Mirrored
on both struct definitions (types.rs canonical + main.rs's
refactoring-leftover duplicate) so the schema is consistent.

`#[serde(skip_serializing_if = "Option::is_none")]` keeps existing
WebSocket consumers unaffected — old clients see no extra field
unless the server populates it. No PerNodeFeatureInfo literal
construction sites exist today (all `node_features: None`), so this
is a schema-only addition; live population from
`NodeState::last_novelty_score` lands in a Pass 3.6 follow-up that
also wires `node_features: Some(...)` at the per-node ESP32 frame
emit path.

Validated:
- cargo test --workspace --no-default-features → 1,561 passed,
  0 failed, 8 ignored (no change; schema-only).
- ESP32-S3 on COM7 streaming live CSI (cb #2100, fresh boot).

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

v2/crates/wifi-densepose-sensing-server/src/main.rs

@@ -476,6 +476,13 @@ struct PerNodeFeatureInfo {
     last_seen_ms: u64,
     frame_rate_hz: f64,
     stale: bool,
+    /// ADR-084 Pass 3 cluster-Pi novelty score in `[0.0, 1.0]`.
+    /// `0.0` = exact-match-in-bank, `1.0` = no overlap with recent
+    /// per-node frame history. `None` until the first
+    /// `update_novelty()` call. Consumers (model-wake gate, anomaly
+    /// emit, UI heatmap) read this to decide whether to escalate.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    novelty_score: Option<f32>,
 }
 
 /// Shared application state

v2/crates/wifi-densepose-sensing-server/src/types.rs

@@ -203,6 +203,11 @@ pub struct PerNodeFeatureInfo {
     pub rssi_dbm: f64,
     pub last_seen_ms: u64,
     pub frame_rate_hz: f64,
+    /// ADR-084 Pass 3 cluster-Pi novelty score in `[0.0, 1.0]`.
+    /// `0.0` = exact-match-in-bank, `1.0` = no overlap with recent
+    /// per-node frame history. `None` until first `update_novelty()`.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub novelty_score: Option<f32>,
     pub stale: bool,
 }