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/core/class-image-nsfw-retry.php

@@ -4,8 +4,8 @@ declare(strict_types=1);
 /**
  * Single-shot retry of NSFW-blocked image slots with a sanitized prompt.
  *
- * When an image provider (currently only Cloudflare Workers AI) rejects a
- * prompt via its content filter, its batch result carries
+ * When an image provider rejects a prompt via its content filter, its
+ * batch result carries
  * `['error_type' => 'nsfw_blocked']`. This helper reruns just the blocked
  * slot once with the rule-based fallback prompt (article title + style
  * suffix, no LLM rewrite) and merges the new result back into the batch.