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

docs/RAIN_ON_WATER_GUIDE.md

@@ -0,0 +1,81 @@
+# 🌊💧 RAIN ON WATER - IMPLEMENTATION GUIDE
+
+## Koncept:
+Ko dež pada, naj se na water tiles pojavljajo majhni ripple effecti (krožni valovi).
+
+## Implementacija:
+
+### 1. Dodaj Rain Impact Detection
+V GameScene.js, v rain particle emitter dodaj callback ko particle umre:
+
+```javascript
+createRainParticles() {
+    // ... existing code ...
+    
+    this.rainEmitter = this.add.particles(0, 0, 'raindrop', {
+        // ... existing config ...
+        
+        // NEW: Detect when raindrop hits ground
+        deathCallback: (particle) => {
+            // Get world position of raindrop
+            const worldX = particle.x;
+            const worldY = particle.y;
+            
+            // Check if hit water tile
+            this.checkRainImpactOnWater(worldX, worldY);
+        }
+    });
+}
+
+### 2. Check If Rain Hit Water
+```javascript
+checkRainImpactOnWater(worldX, worldY) {
+    // Convert screen to grid
+    const gridPos = this.terrainSystem.iso.toGrid(
+        worldX - this.terrainSystem.offsetX,
+        worldY - this.terrainSystem.offsetY
+    );
+    
+    const x = Math.floor(gridPos.x);
+    const y = Math.floor(gridPos.y);
+    
+    // Get tile at position
+    const tile = this.terrainSystem.getTile(x, y);
+    
+    // If water tile, create ripple!
+    if (tile && tile.type === 'water') {
+        this.createWaterRipple(worldX, worldY);
+    }
+}
+```
+
+### 3. Create Water Ripple Effect
+```javascript
+createWaterRipple(x, y) {
+    // Small expanding circle
+    const ripple = this.add.circle(x, y, 2, 0xffffff, 0.6);
+    ripple.setDepth(500); // Above water
+
+    this.tweens.add({
+        targets: ripple,
+        radius: 12,
+        alpha: 0,
+        duration: 400,
+        ease: 'Quad.easeOut',
+        onComplete: () => ripple.destroy()
+    });
+}
+```
+
+---
+
+## Rezultat:
+- Vsaka dežna kapljica ki pade na vodo ustvari majhen ripple
+- Ripple se širi in izgine
+- Creates realistic rain-on-water effect
+
+---
+
+**Status:** Ready to implement  
+**Files to modify:** GameScene.js  
+**Difficulty:** Medium