Statistical RT60 result claims airabsorption:false; dispose leaks the result

[rdmiller]

The Statistical RT60 result is created with info.airabsorption: false even though Sabine/Eyring/Arau all add an air term. UI that keys off that flag will tell the user air is off. K = RT_CONSTANTS[units] is 0.161 at 20 °C only; dispose() does not REMOVE_RESULT.

Found on varese-dev.

info: {
  frequency: this.frequencies,
  airabsorption: false,       // lie
  temperature: this.temperature,
  humidity: this.humidity,    // frozen at first Calculate
}

Subsequent Calculate UPDATE_RESULTs replace data and leave info stale if T/RH changed.

downloadRT60AsCSV exists; toFixed on NaN (empty-room α, zero area) becomes "NaN" in the file. Constructor this.uuid = uuid() after super(props) drops a restored uuid (same pattern as Energy Decay).

Suggested fix

airabsorption: true. Refresh info on every Calculate. K = 24 * Math.LN10 / ac.soundSpeed(T) (metric) with a feet conversion. dispose emits REMOVE_RESULT. Do not re-uuid in the constructor.

Acceptance criteria

• Result panel / CSV reflects that air is included
• Changing room T/RH and re-Calculate updates info
• Deleting the solver removes the Statistical RT60 result