Scale telemetry: SoC temp, weight-stall watchdog, reset reason

[skialpine]

Summary

Diagnostics for field reports of "weight stops being collected under sustained multi-protocol load" — the only recovery seen was a long battery-out cooldown (a quick power-cycle didn't help), pointing at a thermal/analog failure rather than firmware state. Adds telemetry to confirm/rule it out, with no behavior change to the weight/WiFi/BLE paths.

New fields in the /snapshot WS status frame (and serial logs):

• soc_temp_c / soc_temp_max_c — live + peak ESP32-S3 die temp (temperatureRead()), sampled every 2 s.
• weight_stalled / stall_count / last_stall_ms / last_stall_temp_c — a watchdog in pureScale() that flags when the ADS1232 raw value is frozen/railed >8 s (a live cell dithers every sample), recording the die temp at failure to correlate stalls with heat. Skipped during the deliberate ADC power-cycle recovery; throttled to 250 ms.
• reset_reason — esp_reset_reason() at boot, so a brownout/panic/WDT reset is attributable.

Plus tools/thermal_load_test.sh: a 1-hour USB+WiFi+churn+mDNS soak that polls the telemetry (BT driven externally).

Threading: new cross-task scalars are volatile per CLAUDE.md; the status frame only reads them.

Test plan

• Builds for esp32s3; flashed; status frame reports the new fields.
• 1-hour multi-protocol soak to capture peak temp + any stall and the die temp at which it occurs.

🤖 Generated with Claude Code

[skialpine]

Code review

Reviewed the telemetry diff (deep bug scan + threading/CLAUDE.md check). Found one real issue, now fixed in this PR (commit 8e345d9):

• Stall watchdog false-trip during ADC recovery — the watchdog read getDebugInfo().rawValue, which is frozen by definition during the firmware's own powerDown()/powerUp() recovery, so a genuine signal-timeout recovery would be miscounted as a railed/frozen stall (corrupting the very metric this adds). Fixed: skip the check while b_adc_recovery_active and re-seed the window on resume.
• Also (cost): it ran getDebugInfo() (which does a sqrt + dataset passes) every loop iteration though only rawValue is used — wasteful on a chip we're characterizing for heat. Now throttled to 250 ms (the ADC only samples ~10/s).

Verified clean: printf format/arg pairing in both status frames; cross-task reads are volatile (benign torn read only); temperatureRead()/resetReasonStr() safe; at-rest false-positive risk is low (24-bit raw at SAMPLES=1 dithers every sample, so 8 s of byte-identical raw is a genuine freeze).

🤖 Generated with Claude Code