Extends MetricsProvider with thermals() returning a ThermalSnapshot
(battery_percent, battery_temp_c, cpu_temp_c — all optional). Each
provider implements it independently:
- AndroidMetricsProvider reads /sys/class/power_supply/battery/{capacity,
temp} (battery temp is tenths of degC) and walks
/sys/class/thermal/thermal_zone*, filtering by zone type
(cpu/soc/tsens/core) so battery and skin sensors don't dominate the
reading. Rejects nonsense values like INT_MAX from buggy zones.
- PsutilMetricsProvider uses sensors_battery() and
sensors_temperatures() when present (Linux+laptops); no-ops on
Windows/macOS where psutil doesn't expose them.
- NullMetricsProvider returns the empty snapshot.
PerformanceResponse gains battery_percent / battery_temp_c / cpu_temp_c.
The metrics-history ring buffer also carries cpu_temp / battery_pct /
battery_temp per sample so the dashboard can graph them over time.
Frontend dashboard (perf-charts.ts) gets a new Temperature chart card,
hidden by default and revealed only after seed/poll confirms the
backend reports cpu_temp_c. Battery temperature shows inline as a
secondary badge. The GPU card now also hides entirely when the backend
reports gpu=null instead of showing an "unavailable" placeholder.
HOST_ONLY_KEYS prevents the System/App/Both toggle from flipping a
non-existent app dataset for temp.
Tests: 6 new for thermals (battery tenths-of-degC parsing, CPU zone
filtering, fallback when sensors absent, INT_MAX rejection); 18 metrics
tests total; full suite 733 passing.
alexei.dolgolyov
ecae05d00b