feat: redesign UI and UX around design-engineering principles

- Ink-first palette, drop gradients/glow; tabular numbers
- Home: form stays put, results stack below and auto-copy; paste shortens instantly
- Hold-to-delete replaces the delete confirm modal
- Copy buttons morph to a check instead of toasting
- Motion: CSS press feedback, custom ease-out, origin-aware menu, faster exits,
  no animation on frequent/keyboard actions, reduced-motion respected
- Fix: scheme-less URLs ("example.com") were blocked by native validation

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/components/ThemeToggle.tsx

@@ -1,4 +1,3 @@
-import { AnimatePresence, motion } from "framer-motion";
 import { useTheme } from "../context/ThemeContext";
 import { Sun, Moon } from "./icons";
 
@@ -10,20 +9,12 @@ export function ThemeToggle() {
     <button
       onClick={toggle}
       aria-label={dark ? "Switch to light mode" : "Switch to dark mode"}
-      className="focusable relative grid h-9 w-9 place-items-center overflow-hidden rounded-lg border border-line bg-surface text-muted hover:text-ink"
+      className="press focusable grid h-9 w-9 place-items-center rounded-lg text-muted hover:bg-surface-2 hover:text-ink"
     >
-      <AnimatePresence mode="wait" initial={false}>
-        <motion.span
-          key={theme}
-          initial={{ y: 12, opacity: 0 }}
-          animate={{ y: 0, opacity: 1 }}
-          exit={{ y: -12, opacity: 0 }}
-          transition={{ duration: 0.18, ease: "easeOut" }}
-          className="grid place-items-center"
-        >
-          {dark ? <Moon size={17} /> : <Sun size={17} />}
-        </motion.span>
-      </AnimatePresence>
+      <span className="swap">
+        <Sun size={17} data-off={dark} />
+        <Moon size={17} data-off={!dark} />
+      </span>
     </button>
   );
 }