Added configurable CO2 API backend: Nowtricity (default) or Wattnet.

[pailozka]

• Introduced [CO2_API] section with TYPE selector (nowtricity|wattnet).
• Nowtricity settings: BASE_URL, ZONE, USER_AGENT, API_KEY (unified prefix).
• Wattnet settings: URL, API_KEY, ZONE, FOOTPRINT_TYPE, SCOPE.
• Removed hardcoded Nowtricity API URLs — configurable via config.ini.

[pailozka]

questionable if feeding padded data into decisions is the right approach. rather fail loudly:
if len(result) < 24: raise ValueError(f"Wattnet API returned only {len(result)}/24 hourly values")

it is consistent with the fallback logic here:

throttlepoint/src/hpc_eff/utils/controller.py

Lines 173 to 184 in cb523c5

	try:
	historical_values, current_value, median_value, grade = co2_value({
	'User-Agent': config['API']['USER_AGENT'],
	'X-Api-Key': config['API']['API_KEY']
	})
	debug_log(f"Last 24 hours CO2 values (g CO2eq/kWh): {historical_values}")
	debug_log(f"Current CO2 value (g CO2eq/kWh): {current_value}")
	debug_log(f"Median value from 24 hours values (g CO2eq/kWh): {median_value}")
	debug_log(f"Current CO2 value grade from 1 (low) to 10 (high): {grade}")
	except Exception as e:
	historical_values, current_value, median_value, grade = None, None, None, "unknown"
	debug_log(f"Error fetching co2 values and rating: {e}")