feat: UB-style tile processing — white transparent, color remapping

Process each tile through canvas pixel manipulation:
- White pixels → transparent (same as UB's MakeTransparent)
- Remap UB's 5 source colors (walls, inner walls, ramps, floors, stairs)
  to readable display colors on dark background
- Black outlines made semi-transparent
- Current floor at 85% opacity, other floors at 12%
- Non-current floors drawn first, current floor on top

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

static/script.js

@@ -3586,21 +3586,85 @@ function openPlayerDashboard() {
 
 const radarWindows = {};  // character_name -> window element
 const dungeonMapCache = {};  // landblock hex string -> dungeon map data
-let dungeonTileImages = null;  // env_id -> Image, loaded once
+let dungeonTileCanvases = null;  // env_id -> processed offscreen canvas
+
+// UB default source colors (ARGB as signed int32 → R,G,B)
+// These are the colors embedded in the tile images that get remapped
+const UB_TILE_COLORS = {
+  walls:       { r: 0,   g: 0,   b: 255 },  // -16777089 → #0000FF
+  innerWalls:  { r: 127, g: 127, b: 255 },  // -8404993  → #7F7FFF
+  rampedWalls: { r: 77,  g: 255, b: 255 },  // -11622657 → #4DFFFF (approx)
+  floors:      { r: 0,   g: 127, b: 255 },  // -16744513 → #007FFF
+  stairs:      { r: 0,   g: 63,  b: 255 },  // -16760961 → #003FFF
+};
+
+// Target display colors (UB-like appearance on dark background)
+const DUNGEON_DISPLAY_COLORS = {
+  walls:       { r: 140, g: 140, b: 180 },  // light gray-blue walls
+  innerWalls:  { r: 100, g: 100, b: 140 },  // darker inner walls
+  rampedWalls: { r: 120, g: 160, b: 120 },  // greenish ramps
+  floors:      { r: 60,  g: 80,  b: 60  },  // dark green floors
+  stairs:      { r: 180, g: 160, b: 80  },  // yellowish stairs
+};
+
+// Process a tile image: make white transparent, remap UB colors
+function processTileImage(img) {
+  const c = document.createElement('canvas');
+  c.width = 10;
+  c.height = 10;
+  const ctx = c.getContext('2d');
+  ctx.drawImage(img, 0, 0, 10, 10);
+  const imageData = ctx.getImageData(0, 0, 10, 10);
+  const d = imageData.data;
+
+  for (let i = 0; i < d.length; i += 4) {
+    const r = d[i], g = d[i+1], b = d[i+2];
+
+    // Make white (and near-white) transparent
+    if (r > 240 && g > 240 && b > 240) {
+      d[i+3] = 0; // alpha = 0
+      continue;
+    }
+
+    // Color remap: match source colors and replace with display colors
+    let matched = false;
+    for (const [key, src] of Object.entries(UB_TILE_COLORS)) {
+      if (Math.abs(r - src.r) < 15 && Math.abs(g - src.g) < 15 && Math.abs(b - src.b) < 15) {
+        const dst = DUNGEON_DISPLAY_COLORS[key];
+        d[i] = dst.r; d[i+1] = dst.g; d[i+2] = dst.b;
+        matched = true;
+        break;
+      }
+    }
+
+    // Make black semi-transparent (outlines)
+    if (!matched && r < 15 && g < 15 && b < 15) {
+      d[i+3] = 100;
+    }
+  }
+
+  ctx.putImageData(imageData, 0, 0);
+  return c;
+}
 
 // Load dungeon tile textures (614 tiles, ~287KB JSON)
 function loadDungeonTiles() {
-  if (dungeonTileImages) return; // already loading/loaded
-  dungeonTileImages = {};
+  if (dungeonTileCanvases) return; // already loading/loaded
+  dungeonTileCanvases = {};
   fetch('dungeon_tiles.json')
     .then(r => r.json())
     .then(data => {
+      let loaded = 0;
+      const total = Object.keys(data).length;
       Object.entries(data).forEach(([envId, dataUrl]) => {
         const img = new Image();
+        img.onload = () => {
+          dungeonTileCanvases[envId] = processTileImage(img);
+          loaded++;
+          if (loaded === total) console.log(`Processed ${total} dungeon tiles`);
+        };
         img.src = dataUrl;
-        dungeonTileImages[envId] = img;
       });
-      console.log(`Loaded ${Object.keys(dungeonTileImages).length} dungeon tile textures`);
     })
     .catch(err => console.warn('Failed to load dungeon tiles:', err));
 }
@@ -3791,7 +3855,7 @@ function updateRadarWindow(msg) {
     ctx.translate(cx, cy);
     ctx.rotate(-playerHeading * Math.PI / 180); // heading-up rotation
     const cellSize = 10 * scale; // each cell is 10 game units
-    const hasTiles = dungeonTileImages && Object.keys(dungeonTileImages).length > 0;
+    const hasTiles = dungeonTileCanvases && Object.keys(dungeonTileCanvases).length > 0;
 
     // Normalize rotation value to radians (same as UB's DungeonCell.cs)
     function cellRotation(rot) {
@@ -3801,21 +3865,28 @@ function updateRadarWindow(msg) {
       return 0;
     }
 
-    (dmap.z_levels || []).forEach(level => {
+    // Draw non-current floors first (dimmed), then current floor on top
+    const sortedLevels = (dmap.z_levels || []).slice().sort((a, b) => {
+      const aCur = a.z === playerRoundedZ ? 1 : 0;
+      const bCur = b.z === playerRoundedZ ? 1 : 0;
+      return aCur - bCur; // current floor drawn last (on top)
+    });
+
+    sortedLevels.forEach(level => {
       const isCurrentFloor = (level.z === playerRoundedZ);
-      ctx.globalAlpha = isCurrentFloor ? 0.7 : 0.15;
+      ctx.globalAlpha = isCurrentFloor ? 0.85 : 0.12;
 
       (level.cells || []).forEach(cell => {
         const dx = (cell.x - playerX) * scale;
         const dy = -(cell.y - playerY) * scale; // Y flipped
-        const tileImg = hasTiles ? dungeonTileImages[String(cell.env_id)] : null;
+        const tileCanvas = hasTiles ? dungeonTileCanvases[String(cell.env_id)] : null;
 
-        if (tileImg && tileImg.complete && tileImg.naturalWidth) {
-          // Draw textured tile with rotation
+        if (tileCanvas) {
+          // Draw processed tile with rotation
           ctx.save();
           ctx.translate(dx, dy);
           ctx.rotate(cellRotation(cell.rotation));
-          ctx.drawImage(tileImg, -cellSize / 2, -cellSize / 2, cellSize, cellSize);
+          ctx.drawImage(tileCanvas, -cellSize / 2, -cellSize / 2, cellSize, cellSize);
           ctx.restore();
         } else {
           // Fallback: colored rectangle