Extract energy-usage chart data from a utility-bill PDF.

Returns the full page text as Markdown, structured chart data as JSON, and optionally an annotated PNG of the chart region.

Provide exactly one of pdf_path, pdf_base64, or pdf_url.

The result includes a 'series' list. When the chart contains multiple utility types (e.g. electricity and gas on the same chart), each type is returned as a separate Series entry with its own 'id' ('s0', 's1', …) and 'color'. The caller is responsible for determining which series corresponds to which utility — use the bar colors, the series order, and the page Markdown context to make that determination.