fix(v2): full v1-style radar canvas + inventory icon composites

Radar — now pixel-accurate reproduction of v1:
- 300×300 canvas with dark circular background
- Semi-transparent dereth.png map overlay (heading-rotated)
- 4 range rings + crosshair lines
- Compass labels (N=red, E/S/W=gray) rotating with heading
- Facing direction indicator line
- Entity dots color-coded by type (Monster=red, Player=blue,
  NPC=green, Portal=purple, Corpse=orange, Container=yellow)
- Player dot: gold center with white border
- Heading-up rotation for all entity positions
- Click to select entity (white selection ring)
- Scroll to zoom (0.02-5.0 AC units range)
- Entity list with color dot, name, type, distance, compass direction
- Selected entity highlighted with blue left border

Inventory — v1-style icon composites + slot styling:
- 3-layer icon composite: underlay → base → overlay images
  using portal.dat offset formula + icon_overlay_id/IntValues
- Equipment slots: 3D beveled border + cyan glow when equipped
  (matching v1's outset border + #00ffff shadow)
- Pack item cells: purple gradient background (v1's #3d007a)
- Proper 36×36px icon rendering with pixelated scaling

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/components/windows/WindowRenderer.tsx

@@ -36,11 +36,9 @@ export const WindowRenderer: React.FC<Props> = ({ characters, chatMessages, near
             return <CharacterWindow key={w.id} id={w.id} charName={charName} zIndex={w.zIndex} />;
           case 'inv':
             return <InventoryWindow key={w.id} id={w.id} charName={charName} zIndex={w.zIndex} />;
-          case 'radar': {
-            const radarData = nearbyObjects.get(charName);
+          case 'radar':
             return <RadarWindow key={w.id} id={w.id} charName={charName} zIndex={w.zIndex}
-                     socket={socket} nearbyObjects={radarData?.objects ?? []} />;
-          }
+                     socket={socket} radarData={nearbyObjects.get(charName) ?? null} />;
           case 'combat':
             return <CombatStatsWindow key={w.id} id={w.id} charName={charName} zIndex={w.zIndex} />;
           case 'issues':