Create a meme from a template

Create a meme by POSTing raw text. The response includes a canonical url field with path escaping applied — prefer this over hand-built GET URLs when text contains spaces or reserved characters.

Body fields:

• template_id: Template to render (GET /templates/).
• text: Lines of text in order (raw, not escape-encoded). Up to the template's lines value; pass an empty string for an empty intermediate line.
• style: Style names from the template's styles field, or HTTPS URLs for custom overlay images. When overlays > 1, the array sets each slot.
• extension: Output image extension.
• redirect: If true, returns 302 to the canonical URL instead of JSON.