fix: multistatic canonicalization, csi_fps burst inflation, control-packet starvation (#1170, #1180, #1183) (#1193)

#1170 — live multistatic bridge fed raw, un-canonicalized per-node CSI
(64/128/192 bins) to MultistaticFuser, tripping DimensionMismatch every
cycle and silently disabling fusion on mixed HT20/HT40 meshes. Add
HardwareNormalizer::resample_to_canonical (resample-only, no z-score) and
canonicalize every node frame onto the 56-tone grid before fusion.

#1180 — update_csi_fps_ema only rejected dt<=0 or >=1s, so sub-ms UDP-burst
arrivals (36us -> ~27kHz) inflated csi_fps_ema 40-840x. Add a 5ms plausibility
floor and stop re-anchoring observe_csi_frame_arrival on burst deltas.

#1183 — global ENOMEM backoff (CSI flood) starved <=48B/<=1Hz control packets.
Add stream_sender_send_priority() bypassing the backoff gate without touching
the streak; route feature_state/HEALTH/sync through it. Fix the misleading
"HEALTH sent" log that printed even on rv_mesh_send failure.

Verified: signal 501, sensing-server 677 tests (0 failed); firmware builds clean.


Claude-Session: https://claude.ai/code/session_01AgpTcBLRJ32hUsKWxDXf36

firmware/esp32-csi-node/main/rv_mesh.c

@@ -188,7 +188,9 @@ size_t rv_mesh_encode_calibration_start(uint8_t sender_role,
 esp_err_t rv_mesh_send(const uint8_t *frame, size_t len)
 {
     if (frame == NULL || len == 0) return ESP_ERR_INVALID_ARG;
-    int sent = stream_sender_send(frame, len);
+    /* Mesh control packets (HEALTH, anomaly) are low-rate and tiny — send them
+     * on the priority path so the CSI ENOMEM backoff can't starve them (#1183). */
+    int sent = stream_sender_send_priority(frame, len);
     if (sent < 0) {
         ESP_LOGW(TAG, "rv_mesh_send: stream_sender failed (len=%u)",
                  (unsigned)len);