R0: design foundations — reference tokens, motion set, lucide primitives

- globals.css @theme merged with the measured reference system
  (docs/tokens.css): hover/divider/subtle-fg colors, cream + bubble
  tokens, squircle/toggle radii, spec-verbatim shadow set (bubble, card,
  dialog, dock-tile, CTA glow, launcher glow, screen-card ambient, dock
  capsule), marketing light palette, default 0.25s ease-app transition
  tokens. Legacy aliases (--color-accent, --spacing-rail/panel-*)
  retained so existing classes keep working
- motion.css: full app-shell choreography (zoom-in/out from tile origin
  w/ --app-origin-scale, push/pop slides, cross-fade) + messageSlideIn,
  create-claw step/swatch, device-* set — keyframes verbatim from
  docs/motion.md
- lucide-react installed (ISC). New tested primitives: Button (cream/
  coral/ghost/icon/launcher variants per measured states), GradientGlyph
  (per-instance coral linearGradient stroke, the reference glyph
  technique), SegmentedTabs, Card + SectionLabel + GroupedRows,
  SearchPill; Avatar extended (squircle r17, rail/chat/welcome sizes,
  online-dot overlay)

82 unit tests; functional e2e suite green (visual baselines regenerate
in R7).

Co-Authored-By: Claude Fable 5 <[email protected]>

frontend/src/components/ui/SearchPill.tsx

@@ -0,0 +1,24 @@
+"use client";
+
+import { Search } from "lucide-react";
+import type { InputHTMLAttributes } from "react";
+
+/* Rounded search pill (measured): full radius, raised fill, leading
+   search glyph, muted placeholder. */
+export function SearchPill({
+  className,
+  ...rest
+}: InputHTMLAttributes<HTMLInputElement>) {
+  return (
+    <span
+      className={`flex items-center gap-2 rounded-radius-button bg-surface-warm-muted px-3 py-1.5${className ? ` ${className}` : ""}`}
+    >
+      <Search aria-hidden size={14} className="shrink-0 text-subtle-foreground" />
+      <input
+        type="search"
+        className="w-full bg-transparent text-sm text-foreground outline-none placeholder:text-subtle-foreground"
+        {...rest}
+      />
+    </span>
+  );
+}