feat(ui): cohesive frontend polish — design system + per-screen refinement

Distill the UI into a single, recognizable voice: a precision
instrument for one operator on one machine. Bloomberg-coded chrome,
warm-paper detail surfaces, mono-heavy numerics, with one editorial
serif accent for moments of weight.

Design system
- Three-font stack: Geist Sans (UI), Geist Mono (data), Instrument
  Serif (editorial display). No Inter, no system fonts.
- Two surfaces: dark chrome (--background, --accent, --signal) and
  warm paper detail surfaces (--surface, --surface-ink*).
- Inbox has its own Ticker Tape terminal palette (--tt-*).
- Shared component classes: .eyebrow, .mono, .display, .surface,
  .surface-2, .row-hover, .nav-active, .kbd, .editorial, .hairline.
- --m-* token aliases for the legacy drawer components so test-
  asserted class strings keep resolving to the same hue family.

Drawers (Claim + Remit)
- Editorial display face for totals (paid/adjustment amounts).
- Color-coded money tiles: green-tinted paid card, amber-tinted
  adjustment card when non-zero, muted otherwise.
- Tabs get accent-blue underline + CSS-driven active state.
- Validation banners with proper background opacity + ring-around-
  dot success badge.
- StateHistoryTimeline: dashed border, ring around dots, ↳ prefix
  for remit ids.
- DiagnosesList, PartiesGrid, MatchedRemitCard, CasAdjustmentsPanel:
  refined typography, dashed dividers, italic descriptions, mono
  amounts, font-semibold totals, hover row tints.

Inbox Ticker Tape
- Custom RowCheckbox with sr-only input + amber accent.
- Alternating row striping, hover tints, accent rail with inset
  shadow on selection.
- Refined sparkline with glow at high values.
- BulkBar: bottom-floating bar with amber count chip, larger shadow.
- CandidateBreakdown: animated progress bars with amber gradient.
- InboxHeader: Instrument Serif headline, mono day/date stamp,
  pulsing amber status dot.

Dialogs & search
- NewClaimDialog: editorial title, mono NPI/CPT/amount fields.
- SearchBar: refined input row with mono, footer with pulsing
  loading indicator.
- KeyboardCheatsheet: monogram icon chip, hover row states, refined
  eyebrow header.

Primitives
- StatusBadge / ClaimStateBadge: per-state dot indicators.
- SelectItem: data-[highlighted]:outline tokens for keyboard a11y.
- Table primitives: refined header treatment, hover/focus states.

Tests + build
- 354/354 tests passing across 59 files.
- Vite build clean (53.84 kB CSS / 560.86 kB JS).
- Eyebrow assertions updated to match the consolidated .eyebrow
  class (intact visual contract, abstracted class string).
- Badge variant tokens updated to the polished bg-muted/80 /
  /0.14 opacity scale.

src/components/KeyboardCheatsheet/KeyboardCheatsheet.tsx

@@ -1,6 +1,7 @@
 import { useEffect } from "react";
 import { Keyboard, X } from "lucide-react";
 import { Dialog, DialogContent } from "@/components/ui/dialog";
+import { cn } from "@/lib/utils";
 
 type KeyboardCheatsheetProps = {
   open: boolean;
@@ -84,8 +85,8 @@ export function KeyboardCheatsheet({ open, onClose }: KeyboardCheatsheetProps) {
       <DialogContent
         // Centered modal (DialogContent's default positioning is
         // `left-1/2 top-1/2 -translate-x-1/2 -translate-y-1/2`).
-        // We narrow it to max-w-md and apply the modern palette so
-        // it sits on the same surface as the rest of SP4.
+        // We narrow it to max-w-md and apply the warm-paper palette so
+        // it sits on the same surface as the rest of the detail surfaces.
         //
         // a11y wiring:
         //  - `aria-labelledby` points at the visible <h2> below so
@@ -94,21 +95,27 @@ export function KeyboardCheatsheet({ open, onClose }: KeyboardCheatsheetProps) {
         //  - `aria-describedby={undefined}` suppresses Radix's
         //    missing-description warning; the cheatsheet's content
         //    (key list + helper text) is its own description.
-        className="max-w-md bg-[color:var(--m-surface)] text-[color:var(--m-ink-primary)] border border-[color:var(--m-border-heavy)]/20"
+        className={cn(
+          "max-w-md p-5",
+          "bg-[color:var(--m-surface)] text-[color:var(--m-ink-primary)]",
+          "border border-[color:var(--m-border-heavy)]/20",
+          "shadow-[0_24px_64px_-12px_rgb(0_0_0_/_0.5),inset_0_1px_0_0_rgb(255_255_255_/_0.6)]"
+        )}
         aria-labelledby={CHEATSHEET_TITLE_ID}
         aria-describedby={undefined}
         data-testid="keyboard-cheatsheet"
       >
-        <header className="flex items-center justify-between gap-2 mb-3 pr-10">
+        <header className="flex items-center justify-between gap-2 mb-4 pr-10 pb-3 border-b border-[color:var(--m-border-heavy)]/15">
           <div className="flex items-center gap-2">
-            <Keyboard
-              className="h-4 w-4 text-[color:var(--m-ink-secondary)]"
-              strokeWidth={1.75}
+            <span
               aria-hidden
-            />
+              className="inline-flex h-5 w-5 items-center justify-center rounded-[5px] bg-[color:var(--m-ink-primary)]/8 text-[color:var(--m-ink-secondary)]"
+            >
+              <Keyboard className="h-3 w-3" strokeWidth={2} />
+            </span>
             <h2
               id={CHEATSHEET_TITLE_ID}
-              className="text-[10.5px] font-semibold uppercase tracking-[0.18em] text-[color:var(--m-ink-tertiary)]"
+              className="eyebrow text-[color:var(--m-ink-secondary)]"
             >
               Keyboard
             </h2>
@@ -134,11 +141,11 @@ export function KeyboardCheatsheet({ open, onClose }: KeyboardCheatsheetProps) {
           </button>
         </header>
 
-        <ul className="flex flex-col gap-2.5">
+        <ul className="flex flex-col gap-1">
           {SHORTCUTS.map((s) => (
             <li
               key={s.description}
-              className="flex items-center justify-between gap-3 text-sm"
+              className="flex items-center justify-between gap-3 rounded-md px-2 py-1.5 text-sm transition-colors hover:bg-[color:var(--m-ink-primary)]/[0.04]"
             >
               <div className="flex items-center gap-1.5">
                 {s.keys.map((k) => (
@@ -147,15 +154,15 @@ export function KeyboardCheatsheet({ open, onClose }: KeyboardCheatsheetProps) {
                   </kbd>
                 ))}
               </div>
-              <span className="text-[color:var(--m-ink-secondary)]">
+              <span className="text-[13px] text-[color:var(--m-ink-primary)]">
                 {s.description}
               </span>
             </li>
           ))}
         </ul>
 
-        <p className="mt-4 text-xs text-[color:var(--m-ink-tertiary)]">
-          Press any other key to dismiss.
+        <p className="mt-4 pt-3 border-t border-[color:var(--m-border-heavy)]/15 eyebrow text-[color:var(--m-ink-tertiary)]">
+          Press any other key to dismiss
         </p>
       </DialogContent>
     </Dialog>