style(design): consistency sweep + UX upgrades

- Palette: gray/zinc/slate/neutral → stein, red → fire, amber → erde,
  sky → himmel, green → wald
- Footer: replaced raw rgb with stein tokens
- Radius: unified to rounded-xs across cards, buttons, inputs, pagination
- Buttons: .btn-primary/.btn-secondary now font-medium; added secondary
- Card hover: -translate-y-0.5 + shadow + wald-300 border
- Header active link: wald border-bottom + wald-700 text
- Mobile nav: bigger touch targets + wald active accent
- Pagination: prev/next text labels + wald-500 active state with
  separated shape/color classes to avoid Tailwind conflicts
- Lead paragraph: scoped .markdown > p:first-child for top-level
  MarkdownBlock only via [data-block-type="markdown"]
- Section dividers: subtle wald-200 gradient between content rows
- Global focus-visible ring (wald-500)
- Inline hex → palette tokens (Badge amber, Tag custom-color contrast)
- Font weights snapped to design system (300/400/500/600/700)
- transition-all → transition-colors where only color changes
- Removed em-dashes from user-visible templates

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/lib/components/Card.svelte

@@ -25,19 +25,19 @@
         variant: "tile",
         layout: "stack",
         class:
-          "flex flex-col gap-2 border border-gray-200 bg-white p-4 text-slate-950",
+          "flex flex-col gap-2 border border-stein-200 bg-white p-4 text-stein-900",
       },
       {
         variant: "tile",
         layout: "inline",
         class:
-          "flex flex-row items-start gap-3 border border-gray-200 bg-white p-4 text-slate-950",
+          "flex flex-row items-start gap-3 border border-stein-200 bg-white p-4 text-stein-900",
       },
       {
         variant: "tile",
         layout: "post",
         class:
-          "flex flex-col gap-0 border border-gray-200 bg-white p-0 text-slate-950",
+          "flex flex-col gap-0 border border-stein-200 bg-white p-0 text-stein-900",
       },
     ],
     defaultVariants: { variant: "tile", layout: "stack" },
@@ -46,8 +46,8 @@
   const cardAsLink = cva("", {
     variants: {
       variant: {
-        callout: "cursor-pointer transition-all no-underline text-inherit",
-        tile: "transition-all no-underline hover:border-gray-300",
+        callout: "cursor-pointer transition-colors no-underline text-inherit hover:bg-wald-100",
+        tile: "transition-[transform,box-shadow,border-color] duration-200 no-underline hover:-translate-y-0.5 hover:shadow-md hover:border-wald-300",
       },
     },
     defaultVariants: { variant: "tile" },