Story-led homepage and clearer create controls

The main SlideDrift homepage now uses the story-led product walkthrough that was previously being refined separately. It shows the path from source material to editable carousel, brand-kit styling, editing, pricing, and common questions with a calmer product-led design.

Create controls are clearer when you start from a template. After you choose a template, SlideDrift keeps the selected template visible as a removable cue above the input so you can confirm the design direction before generating.

The generate button and create control chips also received small contrast and responsive polish, including better dark-mode CTA contrast and tighter mobile behavior.