Docs: Enhance README files with beginner-friendly guides (4 languages)

**Configuration Improvements:**
- Add comprehensive "Get AI API Keys" section (DeepSeek + Qwen)
- Split configuration into Beginner Mode and Expert Mode
- Add step-by-step setup guides with placeholder tables
- Add configuration checklist and field explanations
- Document smart default behavior for use_default_coins (v2.0.2)
**Startup/Monitoring Guides:**
- Add detailed 2-step system startup instructions
- Include expected output and error troubleshooting tables
- Add monitoring and graceful shutdown procedures
- Provide health check commands
**AI Decision Flow Updates:**
- Enhance flow diagram with emojis and wider boxes
- Add v2.0.2 improvement markers throughout
- Document position duration tracking
- Document accurate USDT PnL calculation with leverage
- Document enhanced AI freedom for raw data analysis
- Document improved position tracking (symbol_side keys)
- Add "Key Improvements in v2.0.2" summary section
**Code Changes:**
- Simplify config.json.example to beginner-friendly single trader
- Implement smart default: use_default_coins auto-enables when omitted
- Set default to true if false without coin_pool_api_url
**Files Updated:**
- README.md (English): +559 lines
- README.zh-CN.md (Chinese): +527 lines
- README.ru.md (Russian): +634 lines
- README.uk.md (Ukrainian): +521 lines
- config.json.example: Simplified configuration
- config/config.go: Smart default logic
Total: 2068+ additions across all documentation
Co-Authored-By: tinkle-community <tinklefund@gmail.com>

config.json.example

@@ -1,29 +1,21 @@
 {
   "traders": [
     {
-      "id": "qwen_trader",
-      "name": "Qwen AI Trader",
-      "ai_model": "qwen",
-      "binance_api_key": "YOUR_BINANCE_API_KEY_1",
-      "binance_secret_key": "YOUR_BINANCE_SECRET_KEY_1",
-      "qwen_key": "YOUR_QWEN_API_KEY",
-      "initial_balance": 1000.0,
-      "scan_interval_minutes": 3
-    },
-    {
-      "id": "deepseek_trader",
-      "name": "DeepSeek AI Trader",
+      "id": "my_trader",
+      "name": "My AI Trader",
       "ai_model": "deepseek",
-      "binance_api_key": "YOUR_BINANCE_API_KEY_2",
-      "binance_secret_key": "YOUR_BINANCE_SECRET_KEY_2",
+      "binance_api_key": "YOUR_BINANCE_API_KEY",
+      "binance_secret_key": "YOUR_BINANCE_SECRET_KEY",
+      "use_qwen": false,
       "deepseek_key": "YOUR_DEEPSEEK_API_KEY",
+      "qwen_key": "",
       "initial_balance": 1000.0,
       "scan_interval_minutes": 3
     }
   ],
-  "use_default_coins": false,
-  "coin_pool_api_url": "http://x.x.x.x:x/api/ai500/list?auth=",
-  "oi_top_api_url": "http://x.x.x.x:x/api/oi/top?auth=",
+  "use_default_coins": true,
+  "coin_pool_api_url": "",
+  "oi_top_api_url": "",
   "api_server_port": 8080,
   "max_daily_loss": 5.0,
   "max_drawdown": 10.0,