style(frontend): look&feel v2 — layered shadows, sharper radii, mono data register

Colors (GSD palette) untouched. New visual vocabulary across the whole GUI:
- warm-tinted layered shadow tokens (--shadow-xs/sm/md) replacing flat rings;
  cards/dialogs framed with hairline border + real elevation
- strict radii scale: xl cards / lg inputs / md controls / 2xl dialogs;
  buttons move from pills to rounded-md
- third type register: --font-mono + tabular-nums on SQL, timers, dates, ids;
  standardized .thot-label micro-label tier
- prose: framed tables with uppercase headers, elevated code blocks
- SqlViewer badges moved from hardcoded Tailwind greens/reds to success/
  destructive token tints; ResultsPanel inline styles replaced with classes
- artifact gate: first option rendered as filled primary action

Verified offline via Playwright against a mock backend replaying a real psd
session (no VPN needed). tsc clean, 115/115 vitest.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/widgets/ReservedControls.tsx

@@ -28,13 +28,13 @@ export function ReservedControls({
       {otherOpen && (
         <div className="flex flex-col gap-2">
           <textarea
-            className="min-h-20 w-full resize-y rounded-lg border border-input bg-card p-3 text-sm outline-none transition-colors focus:border-primary/40 focus:ring-2 focus:ring-ring/20"
+            className="min-h-20 w-full resize-y rounded-lg border border-input bg-card p-3 text-sm shadow-xs outline-none transition-[border-color,box-shadow] focus:border-primary/50 focus:ring-2 focus:ring-ring/20"
             value={text}
             onChange={(e) => setText(e.target.value)}
             placeholder="Describe your alternative…"
           />
           <button
-            className="self-start rounded-lg bg-primary px-3 py-1.5 text-sm font-medium text-primary-foreground transition-colors hover:bg-[oklch(var(--primary-hover))] disabled:cursor-not-allowed disabled:opacity-50"
+            className="self-start rounded-md bg-primary px-3 py-1.5 text-sm font-semibold text-primary-foreground shadow-xs transition-colors hover:bg-[oklch(var(--primary-hover))] disabled:cursor-not-allowed disabled:opacity-50"
             disabled={!text.trim()}
             onClick={() => onControl("freetext", text)}
           >