refactor: simplify deployment - unified env and startup script

- Remove Docker deployment files (1panel doesn't use Docker)
- Unify .env files: .env.example -> .env (single config file)
- Merge start.sh and start-prod.sh into unified start.sh with --prod flag
- Update setup_dev_env.sh to use .env instead of .env.local
- Add DEPLOY.md with 1panel deployment guide

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.env.example

@@ -1,69 +1,35 @@
-# Tool_OCR - Environment Configuration Template
-# Copy this file to .env.local and fill in your actual values
-#
-# Note: Most path configurations have sensible defaults in config.py
-# Only override if you need custom paths
+# Tool_OCR - 環境變數配置
+# 複製此檔案為 .env 並填入實際值
+# cp .env.example .env
 
-# ===== Database Configuration (Required) =====
+# ===== 資料庫 =====
 MYSQL_HOST=your-mysql-host
 MYSQL_PORT=3306
 MYSQL_USER=your-username
 MYSQL_PASSWORD=your-password
 MYSQL_DATABASE=your-database
 
-# ===== Application Configuration =====
-# Server ports
-BACKEND_HOST=0.0.0.0
+# ===== 服務端口 =====
+# IT 會指派實際端口
 BACKEND_PORT=8000
-FRONTEND_HOST=0.0.0.0
 FRONTEND_PORT=5173
 
-# Security (generate a random string for production: openssl rand -hex 32)
-SECRET_KEY=your-secret-key-here-please-change-this-to-random-string
-ALGORITHM=HS256
-ACCESS_TOKEN_EXPIRE_MINUTES=1440
+# ===== 安全性 =====
+# 生產環境請使用: openssl rand -hex 32
+SECRET_KEY=your-secret-key-change-this
 
-# ===== External Authentication Configuration (Required) =====
+# ===== 外部認證 =====
 EXTERNAL_AUTH_API_URL=https://your-auth-api.example.com
 EXTERNAL_AUTH_ENDPOINT=/api/auth/login
-EXTERNAL_AUTH_TIMEOUT=30
-TOKEN_REFRESH_BUFFER=300
 
-# ===== Task Management Configuration =====
-DATABASE_TABLE_PREFIX=tool_ocr_
-ENABLE_TASK_HISTORY=true
-TASK_RETENTION_DAYS=30
-MAX_TASKS_PER_USER=1000
-
-# ===== OCR Configuration =====
-# Note: PaddleOCR/PaddleX models are stored in ~/.paddleocr/ and ~/.paddlex/ by default
-OCR_LANGUAGES=ch,en,japan,korean
-OCR_CONFIDENCE_THRESHOLD=0.5
-MAX_OCR_WORKERS=4
-
-# GPU Acceleration Configuration
-FORCE_CPU_MODE=false
-GPU_MEMORY_FRACTION=0.8
-GPU_DEVICE_ID=0
-
-# ===== File Upload Configuration =====
-MAX_UPLOAD_SIZE=52428800
-ALLOWED_EXTENSIONS=png,jpg,jpeg,pdf,bmp,tiff,doc,docx,ppt,pptx
-# Path defaults to backend/uploads - only override if needed
-# UPLOAD_DIR=./uploads
-
-# ===== Translation Configuration (DIFY API) =====
+# ===== 翻譯 API (DIFY) =====
 ENABLE_TRANSLATION=true
 DIFY_BASE_URL=https://your-dify-instance.example.com/v1
 DIFY_API_KEY=your-dify-api-key
-DIFY_TIMEOUT=120.0
-DIFY_MAX_RETRIES=3
-DIFY_MAX_BATCH_CHARS=5000
-DIFY_MAX_BATCH_ITEMS=20
 
-# ===== CORS Configuration =====
-CORS_ORIGINS=http://localhost:5173,http://127.0.0.1:5173
+# ===== CORS =====
+# 根據實際部署的前端 URL 設定
+CORS_ORIGINS=http://localhost:5173
 
-# ===== Logging Configuration =====
+# ===== 日誌 =====
 LOG_LEVEL=INFO
-# LOG_FILE defaults to backend/logs/app.log