feat: Add baseline calibration & presence detection (v1.7)

CALIBRATE command captures per-subcarrier CSI amplitudes over a timed
window and stores the averaged baseline in NVS. PRESENCE command enables
real-time scoring via normalized Euclidean distance against the baseline,
with rolling window averaging and 10s holdoff on state transitions.

New commands: CALIBRATE [3-60|STATUS|CLEAR], PRESENCE [ON|OFF|THRESHOLD]
New NVS keys: bl_amps (blob), bl_nsub, presence, pr_thresh
New STATUS fields: presence=, pr_score=
New events: calibrate=done, presence=0|1

TASKS.md

@@ -2,9 +2,11 @@
 
 **Last Updated:** 2026-02-04
 
-## Current Sprint: v1.6+ — Validation & Measurement
+## Current Sprint: v1.7+ — Presence Tuning & Integration
 
 ### P2 - Normal
+- [ ] Tune presence threshold per room with real-world testing
+- [ ] Pi-side presence event handling in watch daemon
 - [ ] Power consumption measurements using POWERTEST + external meter
 - [ ] Test OTA rollback (flash bad firmware, verify auto-revert)
 - [ ] Create HA webhook automations for deauth_flood / unknown_probe
@@ -16,6 +18,20 @@
 - [ ] Document esp-radar console features
 - [ ] Pin mapping for ESP32-DevKitC V1
 
+## Completed: v1.7 - Baseline Calibration & Presence Detection
+
+- [x] CALIBRATE command (capture N seconds of CSI, average per-subcarrier amplitudes)
+- [x] CALIBRATE STATUS / CALIBRATE CLEAR subcommands
+- [x] Presence scoring (normalized Euclidean distance vs baseline, rolling window of 50)
+- [x] PRESENCE ON/OFF command (NVS persisted, requires valid baseline)
+- [x] PRESENCE THRESHOLD command (0.001-1.0, NVS persisted, default 0.05)
+- [x] Presence events (`EVENT,<hostname>,presence=<0|1> score=<float>`) with 10s holdoff
+- [x] Calibration done event (`EVENT,<hostname>,calibrate=done packets=<n> nsub=<n>`)
+- [x] presence= and pr_score= fields in STATUS reply
+- [x] NVS persistence: bl_amps (blob), bl_nsub (i8), presence (i8), pr_thresh (i32)
+- [x] config_save_blob / config_erase_key NVS helpers
+- [x] n_sub field in csi_features_t, amps_out parameter in csi_extract_features
+
 ## Completed: v1.6 - Power Management
 
 - [x] ESP-IDF power management framework (DFS 240/80 MHz + light sleep)
@@ -151,10 +167,10 @@
 ## Notes
 
 - Adaptive threshold varies by environment; 0.001-0.01 is a good starting range
-- NVS keys: `send_rate`, `tx_power`, `adaptive`, `threshold`, `ble_scan`, `target_ip`, `target_port`, `hostname`, `boot_count`, `csi_mode`, `hybrid_n`, `auth_secret`, `flood_thresh`, `flood_window`, `scan_rate`, `probe_rate`, `powersave`
+- NVS keys: `send_rate`, `tx_power`, `adaptive`, `threshold`, `ble_scan`, `target_ip`, `target_port`, `hostname`, `boot_count`, `csi_mode`, `hybrid_n`, `auth_secret`, `flood_thresh`, `flood_window`, `scan_rate`, `probe_rate`, `powersave`, `presence`, `pr_thresh`, `bl_nsub`, `bl_amps`
 - EVENT packets include sensor hostname: `EVENT,<hostname>,motion=... rate=... wander=...`
 - ALERT_DATA format: `ALERT_DATA,<hostname>,<deauth|disassoc>,<sender_mac>,<target_mac>,<rssi>` or `ALERT_DATA,<hostname>,deauth_flood,<count>,<window_s>`
-- STATUS fields: `uptime=`, `uptime_s=`, `heap=`, `rssi=`, `channel=`, `tx_power=`, `rate=`, `csi_rate=`, `hostname=`, `version=`, `adaptive=`, `motion=`, `ble=`, `target=`, `temp=`, `csi_count=`, `boots=`, `rssi_min=`, `rssi_max=`, `csi_mode=`, `hybrid_n=`, `auth=`, `flood_thresh=`, `powersave=`
+- STATUS fields: `uptime=`, `uptime_s=`, `heap=`, `rssi=`, `channel=`, `tx_power=`, `rate=`, `csi_rate=`, `hostname=`, `version=`, `adaptive=`, `motion=`, `ble=`, `target=`, `temp=`, `csi_count=`, `boots=`, `rssi_min=`, `rssi_max=`, `csi_mode=`, `hybrid_n=`, `auth=`, `flood_thresh=`, `powersave=`, `presence=`, `pr_score=`
 - PROBE_DATA format: `PROBE_DATA,<hostname>,<mac>,<rssi>,<ssid>`
 - Probe requests deduped per MAC (default 10s cooldown, tunable via PROBERATE)
 - mDNS service: `_esp-csi._udp` on data port (for sensor discovery)