Add AI YouTube thumbnail generator UI

[linus145]

Motivation

• Provide a simple, static frontend for an AI-powered YouTube thumbnail generator that lets users preview and customize thumbnails with presets, palettes, alignment, and quick actions.
• Ship a minimal interactive landing page to iterate on UI controls and client-side preview behavior before integrating backend AI/image generation.

Description

• Add index.html containing the landing page markup with hero, live preview, form controls, palettes, and tips.
• Add styles.css implementing the visual design, responsive layout, preview canvas styling, chips, and palette cards.
• Add app.js implementing client-side interactions for style presets, color palettes, text alignment, shuffle, reset, input syncing, and live preview updates.
• Include sample style presets and color palettes and wire up buttons for Generate thumbnail, Surprise me, and Reset actions.

Testing

• Served the static site with python -m http.server 8000 and captured a full-page screenshot using a Playwright script, which completed successfully and produced an artifact screenshot.
• No automated unit tests were added for this frontend-only change.

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Codex Task

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Avoid randomizing state during reset

Calling shuffle() inside the reset handler overrides the default style, palette, and alignment values set just above, so pressing Reset produces a random configuration instead of restoring the initial baseline. In normal UI use this makes the reset action unreliable and prevents users from getting back to the documented default preset combination.

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