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/components/ui/badge.tsx

@@ -5,7 +5,7 @@ import { cva, type VariantProps } from "class-variance-authority"
 import { cn } from "@/lib/utils"
 
 const badgeVariants = cva(
-  "group/badge inline-flex h-5 w-fit shrink-0 items-center justify-center gap-1 overflow-hidden rounded-4xl border border-transparent px-2 py-0.5 text-xs font-medium whitespace-nowrap transition-all focus-visible:border-ring focus-visible:ring-[3px] focus-visible:ring-ring/50 has-data-[icon=inline-end]:pr-1.5 has-data-[icon=inline-start]:pl-1.5 aria-invalid:border-destructive aria-invalid:ring-destructive/20 dark:aria-invalid:ring-destructive/40 [&>svg]:pointer-events-none [&>svg]:size-3!",
+  "group/badge inline-flex h-5 w-fit shrink-0 items-center justify-center gap-1 overflow-hidden rounded-md border border-transparent px-2 py-0.5 text-xs font-medium whitespace-nowrap transition-all focus-visible:border-ring focus-visible:ring-[3px] focus-visible:ring-ring/50 has-data-[icon=inline-end]:pr-1.5 has-data-[icon=inline-start]:pl-1.5 aria-invalid:border-destructive aria-invalid:ring-destructive/20 dark:aria-invalid:ring-destructive/40 [&>svg]:pointer-events-none [&>svg]:size-3!",
   {
     variants: {
       variant: {

frontend/src/components/ui/button.tsx

@@ -4,13 +4,13 @@ import { cva, type VariantProps } from "class-variance-authority"
 import { cn } from "@/lib/utils"
 
 const buttonVariants = cva(
-  "group/button inline-flex shrink-0 items-center justify-center rounded-full border border-transparent bg-clip-padding text-sm font-semibold tracking-[0.005em] whitespace-nowrap transition-all outline-none select-none focus-visible:ring-3 focus-visible:ring-ring/25 active:not-aria-[haspopup]:translate-y-px disabled:pointer-events-none disabled:opacity-50 aria-invalid:border-destructive aria-invalid:ring-3 aria-invalid:ring-destructive/20 dark:aria-invalid:border-destructive/50 dark:aria-invalid:ring-destructive/40 [&_svg]:pointer-events-none [&_svg]:shrink-0 [&_svg:not([class*='size-'])]:size-4",
+  "group/button inline-flex shrink-0 items-center justify-center rounded-md border border-transparent bg-clip-padding text-sm font-semibold tracking-[0.005em] whitespace-nowrap transition-all outline-none select-none focus-visible:ring-3 focus-visible:ring-ring/25 active:not-aria-[haspopup]:translate-y-px disabled:pointer-events-none disabled:opacity-50 aria-invalid:border-destructive aria-invalid:ring-3 aria-invalid:ring-destructive/20 dark:aria-invalid:border-destructive/50 dark:aria-invalid:ring-destructive/40 [&_svg]:pointer-events-none [&_svg]:shrink-0 [&_svg:not([class*='size-'])]:size-4",
   {
     variants: {
       variant: {
-        default: "bg-primary text-primary-foreground hover:bg-[oklch(var(--primary-hover))]",
+        default: "bg-primary text-primary-foreground shadow-xs hover:bg-[oklch(var(--primary-hover))]",
         outline:
-          "border-border bg-background hover:bg-muted hover:text-foreground aria-expanded:bg-muted aria-expanded:text-foreground dark:border-input dark:bg-input/30 dark:hover:bg-input/50",
+          "border-border bg-card shadow-xs hover:bg-muted hover:text-foreground aria-expanded:bg-muted aria-expanded:text-foreground dark:border-input dark:bg-input/30 dark:hover:bg-input/50",
         secondary:
           "bg-secondary text-secondary-foreground hover:bg-[color-mix(in_oklch,oklch(var(--secondary)),oklch(var(--foreground))_5%)] aria-expanded:bg-secondary aria-expanded:text-secondary-foreground",
         ghost:

frontend/src/components/ui/card.tsx

@@ -12,7 +12,7 @@ function Card({
       data-slot="card"
       data-size={size}
       className={cn(
-        "group/card flex flex-col gap-(--card-spacing) overflow-hidden rounded-xl bg-card py-(--card-spacing) text-sm text-card-foreground ring-1 ring-foreground/10 [--card-spacing:--spacing(4)] has-data-[slot=card-footer]:pb-0 has-[>img:first-child]:pt-0 data-[size=sm]:[--card-spacing:--spacing(3)] data-[size=sm]:has-data-[slot=card-footer]:pb-0 *:[img:first-child]:rounded-t-xl *:[img:last-child]:rounded-b-xl",
+        "group/card flex flex-col gap-(--card-spacing) overflow-hidden rounded-xl border border-border/70 bg-card py-(--card-spacing) text-sm text-card-foreground shadow-sm [--card-spacing:--spacing(4)] has-data-[slot=card-footer]:pb-0 has-[>img:first-child]:pt-0 data-[size=sm]:[--card-spacing:--spacing(3)] data-[size=sm]:has-data-[slot=card-footer]:pb-0 *:[img:first-child]:rounded-t-xl *:[img:last-child]:rounded-b-xl",
         className
       )}
       {...props}

frontend/src/components/ui/dialog.tsx

@@ -53,7 +53,7 @@ function DialogContent({
       <DialogPrimitive.Popup
         data-slot="dialog-content"
         className={cn(
-          "fixed top-1/2 left-1/2 z-50 grid w-full max-w-[calc(100%-2rem)] -translate-x-1/2 -translate-y-1/2 gap-4 rounded-xl bg-popover p-4 text-sm text-popover-foreground ring-1 ring-foreground/10 duration-100 outline-none sm:max-w-sm data-open:animate-in data-open:fade-in-0 data-open:zoom-in-95 data-closed:animate-out data-closed:fade-out-0 data-closed:zoom-out-95",
+          "fixed top-1/2 left-1/2 z-50 grid w-full max-w-[calc(100%-2rem)] -translate-x-1/2 -translate-y-1/2 gap-4 rounded-2xl bg-popover p-4 text-sm text-popover-foreground shadow-md ring-1 ring-foreground/10 duration-100 outline-none sm:max-w-sm data-open:animate-in data-open:fade-in-0 data-open:zoom-in-95 data-closed:animate-out data-closed:fade-out-0 data-closed:zoom-out-95",
           className
         )}
         {...props}
@@ -102,7 +102,7 @@ function DialogFooter({
     <div
       data-slot="dialog-footer"
       className={cn(
-        "-mx-4 -mb-4 flex flex-col-reverse gap-2 rounded-b-xl border-t bg-muted/50 p-4 sm:flex-row sm:justify-end",
+        "-mx-4 -mb-4 flex flex-col-reverse gap-2 rounded-b-2xl border-t bg-muted/50 p-4 sm:flex-row sm:justify-end",
         className
       )}
       {...props}

frontend/src/components/ui/textarea.tsx

@@ -7,7 +7,7 @@ function Textarea({ className, ...props }: React.ComponentProps<"textarea">) {
     <textarea
       data-slot="textarea"
       className={cn(
-        "flex field-sizing-content min-h-16 w-full rounded-lg border border-input bg-transparent px-2.5 py-2 text-base transition-colors outline-none placeholder:text-muted-foreground focus-visible:border-ring focus-visible:ring-3 focus-visible:ring-ring/50 disabled:cursor-not-allowed disabled:bg-input/50 disabled:opacity-50 aria-invalid:border-destructive aria-invalid:ring-3 aria-invalid:ring-destructive/20 md:text-sm dark:bg-input/30 dark:disabled:bg-input/80 dark:aria-invalid:border-destructive/50 dark:aria-invalid:ring-destructive/40",
+        "flex field-sizing-content min-h-16 w-full rounded-lg border border-input bg-transparent px-2.5 py-2 text-base shadow-xs transition-[border-color,box-shadow] outline-none placeholder:text-muted-foreground focus-visible:border-ring focus-visible:ring-3 focus-visible:ring-ring/50 disabled:cursor-not-allowed disabled:bg-input/50 disabled:opacity-50 aria-invalid:border-destructive aria-invalid:ring-3 aria-invalid:ring-destructive/20 md:text-sm dark:bg-input/30 dark:disabled:bg-input/80 dark:aria-invalid:border-destructive/50 dark:aria-invalid:ring-destructive/40",
         className
       )}
       {...props}