feat: Complete 2D Visual Overhaul - Isometric to Flat Top-Down

- NEW: Flat2DTerrainSystem.js (375 lines)
- NEW: map2d_data.js procedural map (221 lines)
- MODIFIED: GameScene async create, 2D terrain integration
- MODIFIED: Player.js flat 2D positioning
- MODIFIED: game.js disabled pixelArt for smooth rendering
- FIXED: 15+ bugs (updateCulling, isometric conversions, grid lines)
- ADDED: Phase 28 to TASKS.md
- DOCS: DNEVNIK.md session summary

Result: Working flat 2D game with Stardew Valley style!
Time: 5.5 hours

src/game.js

@@ -45,19 +45,19 @@ const config = {
     height: 768,  // 4:3 aspect ratio
     parent: 'game-container',
     backgroundColor: '#1a1a2e',
-    pixelArt: true,
-    antialias: false,
-    roundPixels: true,
+    pixelArt: false, // 🎨 SMOOTH 2D (was: true)
+    antialias: true, // 🎨 SMOOTH edges (was: false)
+    roundPixels: false, // 🎨 SMOOTH positioning (was: true)
     render: {
-        pixelArt: true,
-        antialias: false,
-        roundPixels: true,
+        pixelArt: false, // 🎨 SMOOTH 2D
+        antialias: true, // 🎨 SMOOTH edges
+        roundPixels: false, // 🎨 SMOOTH positioning
         transparent: false,
         clearBeforeRender: true,
         powerPreference: 'high-performance',
-        premultipliedAlpha: true, // Fix transparency
+        premultipliedAlpha: true,
         failIfMajorPerformanceCaveat: false,
-        // Eksplicitna NEAREST_NEIGHBOR filtracija
+        // 🎨 LINEAR filtering for smooth tiles
         mipmapFilter: 'NEAREST',
         batchSize: 4096
     },