feat(ui): port Direction B layout shell (Phase 1)

Implements the layout-shell phase of the Direction B redesign from the
Anthropic Design handoff bundle.

Visual layer:
- Geist font + new --gd-* CSS token palette (panel/border/text scales,
  green/amber/blue/purple accents alongside the red).
- Top bar with brand chip, origin/destination inputs, chat composer
  with chip-based refinements, vehicle selector chip, Export/Share.
- Body split: map-left flex-1, stops rail 540px right (replaces the
  prior chat-sidebar + bottom-timeline layout).
- Stops rail: trip summary header (stops · days · km · drive · charge),
  sticky day headers with date label + per-day km/drive/charge totals,
  icon-led stop cards with colored type-icon tile (charge/sleep/hotel/
  attraction/cafe/viewpoint colour-coded), combo pill, description,
  charge/arrive meta inline.
- Leg row between cards (km · drive time), still computed from real
  OSRM routes.
- Click stop to expand: 4-stat grid (Charge/Arrive/Leave/Cost),
  amenity chip cloud, alternative-swap list (preserving the existing
  delta swap mechanic), Customise/Remove actions.
- Map ↔ rail bridge: clicking a card flies the map to that pin,
  hovering either highlights the other. Pins are custom Leaflet
  divIcons coloured per stop type with active/hover scaling.
- Empty state + quick-prompt buttons in the rail.

Not in Phase 1 (deferred):
- Variant strip (Fastest/Scenic/Cheapest) — needs backend prompt work.
- While-here food/do/see tabs — needs backend nearby[] data.
- Customise / Add-detour / GPX modals.
- Vehicle selector trim panel (still a native select for now).
- Drag-to-reorder, in-trip/compare/shared screens.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

client/src/styles/globals.css

@@ -1,51 +1,81 @@
+@import url('https://fonts.googleapis.com/css2?family=Geist:wght@300;400;500;600;700&family=Geist+Mono:wght@400;500&display=swap');
+
 @tailwind base;
 @tailwind components;
 @tailwind utilities;
 
 :root {
-  --tesla-red: #E82127;
-  --bg: #0a0a0a;
-  --bg-elevated: #111111;
-  --bg-card: #1a1f2b;
-  --border: rgba(255, 255, 255, 0.08);
+  /* Direction B palette */
+  --gd-bg: #0a0a0c;
+  --gd-bg-2: #111114;
+  --gd-panel: #15151a;
+  --gd-panel-2: #1c1c22;
+  --gd-border: rgba(255, 255, 255, 0.08);
+  --gd-border-2: rgba(255, 255, 255, 0.14);
+  --gd-text: #f5f5f7;
+  --gd-text-2: #a8a8b0;
+  --gd-text-3: #6c6c75;
+  --gd-red: #e31937;
+  --gd-red-soft: rgba(227, 25, 55, 0.14);
+  --gd-red-line: rgba(227, 25, 55, 0.32);
+  --gd-green: #4ade80;
+  --gd-amber: #fbbf24;
+  --gd-blue: #60a5fa;
+  --gd-purple: #c084fc;
+
+  /* Legacy aliases (still referenced in a few places) */
+  --tesla-red: var(--gd-red);
+  --bg: var(--gd-bg);
+  --bg-elevated: var(--gd-bg-2);
+  --bg-card: var(--gd-panel);
+  --border: var(--gd-border);
 }
 
-body {
-  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
-  background-color: var(--bg);
-  color: white;
+html, body, #root {
+  margin: 0;
+  padding: 0;
+  height: 100%;
+  background: var(--gd-bg);
+  color: var(--gd-text);
+  font-family: 'Geist', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
+  letter-spacing: -0.01em;
+  -webkit-font-smoothing: antialiased;
 }
 
-/* Tesla-inspired scrollbar */
+.mono { font-family: 'Geist Mono', ui-monospace, monospace; }
+.num { font-variant-numeric: tabular-nums; font-feature-settings: 'tnum'; }
+
 ::-webkit-scrollbar {
   width: 6px;
   height: 6px;
 }
-::-webkit-scrollbar-track {
-  background: #1a1a1a;
-}
+::-webkit-scrollbar-track { background: transparent; }
 ::-webkit-scrollbar-thumb {
-  background: #3a3a3a;
+  background: rgba(255, 255, 255, 0.12);
   border-radius: 3px;
 }
 ::-webkit-scrollbar-thumb:hover {
-  background: #E82127;
+  background: rgba(255, 255, 255, 0.22);
 }
 
-/* Map container */
 .leaflet-container {
   background: #0a0f1a !important;
+  font-family: inherit;
 }
 
-/* Chat bubbles */
-.chat-bubble-user {
-  background: #E82127;
-  color: white;
-  border-bottom-right-radius: 4px;
+/* Override Leaflet popup styling to match Direction B */
+.leaflet-popup-content-wrapper {
+  background: rgba(20, 20, 24, 0.95);
+  color: var(--gd-text);
+  border: 1px solid var(--gd-border-2);
+  border-radius: 10px;
+  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.4);
 }
-
-.chat-bubble-assistant {
-  background: #1f242e;
-  border: 1px solid rgba(255,255,255,0.08);
-  border-bottom-left-radius: 4px;
+.leaflet-popup-tip {
+  background: rgba(20, 20, 24, 0.95);
+}
+.leaflet-popup-content {
+  margin: 10px 12px;
+  font-size: 12px;
+  line-height: 1.5;
 }