fix(firmware): add vTaskDelay(1) yields in process_frame() at tier>=2 to fix WDT storm (#683)

At edge tier>=2 on N16R8 PSRAM boards, `process_frame()` runs
`update_multi_person_vitals()` (4 persons × 256 history samples) plus
`wasm_runtime_on_frame()` back-to-back before returning to `edge_task()`.
The existing `vTaskDelay(1)` in `edge_task()` only fires *after*
`process_frame()` returns — under sustained 30 pps CSI load on PSRAM
boards this leaves IDLE1 on Core 1 starved long enough for the 5-second
Task Watchdog Timer to fire.

Fix: add two `vTaskDelay(1)` calls inside `process_frame()`, both gated
on `s_cfg.tier >= 2`:
1. After `update_multi_person_vitals()` (Step 11)
2. After `wasm_runtime_on_frame()` dispatch (Step 14)

Tier 0/1 paths are unaffected. Validated on COM7 (N16R8 board):
`Edge DSP task started on core 1 (tier=2)`, no WDT panics in 20 s.

Also bump firmware version 0.6.5 → 0.6.6 and refresh all 6 release_bins
with the new build (8MB + 4MB variants, built 2026-05-21).

Fix-marker RuView#683 added to scripts/fix-markers.json.

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

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

@@ -849,6 +849,8 @@ static void process_frame(const edge_ring_slot_t *slot)
 
     /* --- Step 11: Multi-person vitals --- */
     update_multi_person_vitals(slot->iq_data, n_subcarriers, sample_rate);
+    /* Yield after multi-person DSP so IDLE1 can feed Core 1 watchdog (#683). */
+    if (s_cfg.tier >= 2) vTaskDelay(1);
 
     /* --- Step 12: Delta compression --- */
     if (s_cfg.tier >= 2) {
@@ -894,6 +896,8 @@ static void process_frame(const edge_ring_slot_t *slot)
         wasm_runtime_on_frame(phases, amplitudes, variances,
                               n_subcarriers,
                               (const edge_vitals_pkt_t *)&s_latest_pkt);
+        /* Yield after WASM dispatch to feed Core 1 watchdog (#683). */
+        vTaskDelay(1);
     }
 }
 

firmware/esp32-csi-node/release_bins/version.txt

@@ -1,3 +1,3 @@
-0.6.5
-git-sha: d72e06fc8
-built: 2026-05-20
+0.6.6
+git-sha: cbcb389cb (pre-commit)
+built: 2026-05-21

firmware/esp32-csi-node/version.txt

@@ -1 +1 @@
-0.6.5
+0.6.6