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

SESSION_SUMMARY_2025-12-14.md

@@ -0,0 +1,84 @@
+# 📦 SESSION SUMMARY - 2025-12-14
+
+## 🎯 OBJECTIVE ACHIEVED
+✅ **Complete 2D Conversion** - From Isometric to Flat Top-Down View
+
+---
+
+## ✅ COMPLETED WORK
+
+### 1. NEW SYSTEMS CREATED (600+ lines)
+```
+src/systems/Flat2DTerrainSystem.js  - 375 lines
+data/map2d_data.js                  - 221 lines  
+```
+
+### 2. MAJOR MODIFICATIONS
+```
+src/game.js          - Disabled pixelArt mode
+src/scenes/GameScene.js - 2D terrain, async, fixes
+src/entities/Player.js  - Flat 2D positioning
+index.html           - Added new scripts
+```
+
+### 3. BUG FIXES (15+)
+- updateCulling not found
+- Cloud sprite undefined
+- 4x isometric toGrid conversions
+- getTile array safety checks
+- Grid lines removed
+- Map chaos simplified
+
+### 4. DOCUMENTATION
+```
+DNEVNIK.md                    - Session diary
+TASKS.md                      - Phase 28 added  
+docs/2D_CONVERSION_*.md       - 3 guides
+```
+
+---
+
+## 📊 STATS
+
+**Time:** 5.5 hours  
+**Lines Added:** ~600  
+**Files Created:** 2  
+**Files Modified:** 7  
+**Bugs Fixed:** 15+  
+**Features:** 2D rendering, clean map
+
+---
+
+## 🎮 RESULT
+
+**Before:**
+- ❌ Isometric diamonds
+- ❌ Grid lines
+- ❌ Confusing perspective
+
+**After:**
+- ✅ Flat 2D top-down
+- ✅ Smooth tiles
+- ✅ Professional look
+- ✅ Stardew Valley style
+
+---
+
+## 💾 FILES TO COMMIT
+
+**New:**
+- `src/systems/Flat2DTerrainSystem.js`
+- `data/map2d_data.js`
+- `DNEVNIK.md`
+- `docs/2D_CONVERSION_*.md` (3 files)
+
+**Modified:**
+- `src/game.js`
+- `src/scenes/GameScene.js`
+- `src/entities/Player.js`
+- `index.html`
+- `TASKS.md`
+
+---
+
+**Status:** Ready for commit! 🚀