AirNow Hourly Obs Fetch

Core Goal

• Fetch AirNow Hourly AQ Obs data files for one UTC window.
• Filter rows by mission bounding box and requested pollutant parameters.
• Return one normalized JSON record per site-hour-parameter for downstream processing.
• Keep execution deterministic with retries, throttling, and local safety caps.

Repository Policy

• This is the canonical AirNow station-observation skill in this repository.
• When eco-council or OpenClaw assigns a raw artifact path, write this skill's full JSON payload to that exact path with --output.
• Do not treat dry-run output as collected evidence.

Required Environment

• Configure runtime by environment variables (see references/env.md).
• Start from assets/config.example.env.
• Load env values before running commands: