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/stream_sender.c

@@ -121,6 +121,34 @@ int stream_sender_send(const uint8_t *data, size_t len)
     return sent;
 }
 
+int stream_sender_send_priority(const uint8_t *data, size_t len)
+{
+    if (s_sock < 0) {
+        return -1;
+    }
+
+    /* Priority path (#1183): low-rate control packets (feature_state, HEALTH,
+     * mesh sync) bypass the global ENOMEM backoff gate so the high-rate CSI
+     * stream cannot starve them. These are ≤48 B at ≤1 Hz — negligible pbuf
+     * pressure, so they won't re-trigger the crash cascade that the backoff
+     * (driven by the 50 Hz CSI flood) exists to prevent.
+     *
+     * Crucially, an ENOMEM here is reported quietly and does NOT extend the
+     * global streak/backoff: a tiny control packet failing is a symptom of
+     * the bulk-stream pressure, not a cause, so it must not feed the cooldown
+     * that suppresses the next CSI frame. Likewise a success does not reset
+     * the streak — the bulk path owns that signal. */
+    int sent = sendto(s_sock, data, len, 0,
+                      (struct sockaddr *)&s_dest_addr, sizeof(s_dest_addr));
+    if (sent < 0) {
+        if (errno != ENOMEM) {
+            ESP_LOGW(TAG, "priority sendto failed: errno %d", errno);
+        }
+        return -1;
+    }
+    return sent;
+}
+
 void stream_sender_deinit(void)
 {
     if (s_sock >= 0) {