Add Kontent.ai image provider support

[stefashkaa]

Feature Title

Add Kontent.ai image provider support

Description

Add a Kontent.ai integration using the existing Imgix-style query helpers while restricting behavior to Kontent.ai’s documented transformation API.

Use Case

A Kontent.ai-backed application needs responsive image variants and focal-point crops without assuming every upstream Imgix operation is available.

Proposed Solution

• Add and export kontent through the core provider registry so Angular, React, and Svelte can use the shared configuration.
• Map the documented subset of w, h, fm, q, fit, focal-point controls, and auto=format through shared query-generation logic.
• Validate supported fit and format values against Kontent.ai’s API. Keep provider-specific validation and defaults separate from generic Imgix serialization.
• Preserve asset paths and existing query parameters, and document automatic-format behavior and unsupported operations.
• Add setup documentation and focused fixtures covering supported fit and format values, focal points, automatic format, and existing source parameters. Validate advertised dimensions and content types against an enabled service or controlled server where applicable.

Alternatives Considered

Use the existing imgix provider with manually restricted options or write a custom provider. A Kontent-specific integration would make the documented subset explicit.

Examples from Other Libraries

Unpic includes a Kontent.ai provider in its provider implementations.

• Image transformation API