Build an AI YouTube thumbnail generator web app with these features:

1. Prompt input where users paste a video title, a short script summary, or a niche description (for example: 'How I edit videos 5x faster', tech niche, audience: beginner editors). The AI analyzes the topic and proposes 4 thumbnail concepts, each with an image direction and an overlay text idea of 3 to 5 words.

2. AI image generation: generate thumbnail backgrounds at 1280x720 using an image API, with styles tuned for high CTR: high contrast, expressive faces, dramatic lighting, bold colors. Include style presets (reaction, comparison, before-after, glow-up, money, shocked face).

3. Text overlay engine: render the suggested overlay text on the image with bold sans-serif fonts, stroke and shadow options, and safe-zone placement that avoids the YouTube timestamp corner. Users can edit text, font, size, color, and position.

4. Face mode: users upload their own photo and the app cuts out the face, enlarges it, and composites it over the generated background with outline effects. Support up to 2 faces for reaction-style thumbnails.

5. A/B variants: generate 4 variants per concept with different text, colors, and compositions. Download all or pick a favorite.

6. CTR tracking (optional pro feature): user pastes the published video URL and upload date for each variant, and the app pulls public view counts to show which thumbnail style wins over time, building a personal style report.

7. Brand kit: save channel name, logo, color palette, and default fonts so every thumbnail comes out consistent.

8. Template library: browse 20 thumbnail templates by niche (finance, gaming, tech, vlog, tutorial) and remix them with one click.

9. Compliance guardrails: warn when generated text is unreadable at small sizes (simulate mobile preview at 10 percent scale) and flag misleading or clickbait claims.

10. Export: PNG and JPG at 1280x720, under 2MB, with optional watermark on the free tier.