cf-removal: patch registry, pipeline, settings, admin-page, interface

Wires out the Cloudflare Workers AI image provider across the plugin:

- class-image-pipeline.php: drop 'cloudflare' dispatch branch; Runware
  becomes the unrecognised-provider fallback
- class-image-model-registry.php: remove flux-1-schnell/cloudflare row;
  update provider-enum docblocks (runware|openrouter only)
- class-settings-fields-extended.php: remove three CF fields
  (cloudflare_ai_token, cloudflare_account_id, cf_image_via_gateway);
  drop Cloudflare mention from model-picker + NSFW retry descriptions
- class-admin-page.php: remove prautoblogger_cloudflare_ai_token from
  the encrypted-options list
- interface-image-provider.php: retarget preamble @see at Runware +
  OpenRouter; update get_provider_name() example
- class-image-nsfw-blocked.php: generalise preamble (Runware +
  OpenRouter can raise this)

Also cleans stale CF Workers AI mentions in:
class-ajax-handlers.php, interface-model-registry.php,
class-image-nsfw-retry.php, class-open-router-image-pricing.php,
prautoblogger.php.

The Cloudflare AI Gateway path (in class-open-router-config.php,
class-settings-fields.php 'prautoblogger_ai_gateway_base_url',
class-open-router-request-builder.php cache headers) is intentionally
untouched — it fronts OpenRouter and is unrelated to the CF Workers AI
image provider.

includes/providers/class-image-nsfw-blocked.php

@@ -4,18 +4,18 @@ declare(strict_types=1);
 /**
  * Exception raised when an image provider rejects a prompt as NSFW.
  *
- * Cloudflare Workers AI returns HTTP 400 with an `errors[].code === 3030`
- * body when its content filter blocks a prompt. We catch that shape in
- * the provider and raise this typed exception so the image pipeline can
- * distinguish a content-filter rejection from a generic 4xx and retry
- * once with a sanitized fallback prompt.
+ * Image providers (Runware, OpenRouter) return provider-specific error
+ * shapes when their content filters block a prompt. We catch those shapes
+ * in each provider and raise this typed exception so the image pipeline
+ * can distinguish a content-filter rejection from a generic 4xx and
+ * retry once with a sanitized fallback prompt.
  *
- * Triggered by: PRAutoBlogger_Cloudflare_Image_Provider on NSFW 4xx.
+ * Triggered by: image providers on NSFW-filter rejection.
  * Dependencies: None.
  *
- * @see providers/class-cloudflare-image-provider.php — Raises this.
- * @see core/class-image-nsfw-retry.php               — Catches + rebuilds prompt.
- * @see https://developers.cloudflare.com/workers-ai/models/flux-1-schnell/ — Upstream error codes.
+ * @see providers/class-runware-image-provider.php     — May raise this.
+ * @see providers/class-open-router-image-provider.php — May raise this.
+ * @see core/class-image-nsfw-retry.php                — Catches + rebuilds prompt.
  */
 class PRAutoBlogger_Image_NSFW_Blocked extends \RuntimeException {