Three fixes in one:
1. Duplicate image: prepend_caption_to_post() was embedding the full
image + caption as a <figure> block, but the theme already displays
the featured image. Now only the caption text is prepended — no
second copy of the image.
2. Hardcoded model names: removed all FLUX.1/FLUX.2 references from
model-agnostic code (pipeline, prompt builder, sideloader, OpenRouter
provider, interface, admin labels). The Cloudflare provider still
references FLUX since it specifically wraps that model family.
3. Test alignment: OpenRouterImagePricingTest was asserting against
removed models (flux-2-pro, seedream). Updated to match current
COST_PER_IMAGE entries (Gemini Flash, GPT-5 Image).
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>