feat: unify environment scripts with start.sh

- Add unified start.sh script with subcommands (all/backend/frontend)
- Add process management (--stop, --status)
- Remove separate start_backend.sh and start_frontend.sh
- Update setup_dev_env.sh with pre-flight checks and --cpu-only/--skip-db options
- Update .env.example to remove sensitive data and add DIFY translation config
- Add .pid/ to .gitignore for process management

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

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

.env.example

@@ -1,81 +1,85 @@
 # Tool_OCR - Environment Configuration Template
-# Copy this file to .env and fill in your actual values
+# Copy this file to .env.local and fill in your actual values
 
 # ===== Database Configuration =====
-MYSQL_HOST=mysql.theaken.com
-MYSQL_PORT=33306
-MYSQL_USER=A060
-MYSQL_PASSWORD=WLeSCi0yhtc7
-MYSQL_DATABASE=db_A060
+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_PORT=12010
-FRONTEND_PORT=12011
+BACKEND_PORT=8000
+FRONTEND_PORT=5173
 
-# Security
+# Security (generate a random string for production)
 SECRET_KEY=your-secret-key-here-please-change-this-to-random-string
 ALGORITHM=HS256
-ACCESS_TOKEN_EXPIRE_MINUTES=30
+ACCESS_TOKEN_EXPIRE_MINUTES=1440
+
+# ===== External Authentication Configuration =====
+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 =====
-# PaddleOCR model directory
 PADDLEOCR_MODEL_DIR=./models/paddleocr
-# Supported languages (comma-separated)
 OCR_LANGUAGES=ch,en,japan,korean
-# Default confidence threshold
 OCR_CONFIDENCE_THRESHOLD=0.5
-# Maximum concurrent OCR workers
 MAX_OCR_WORKERS=4
 
+# GPU Acceleration Configuration
+FORCE_CPU_MODE=false
+GPU_MEMORY_FRACTION=0.8
+GPU_DEVICE_ID=0
+
 # ===== File Upload Configuration =====
-# Maximum file size in bytes (50MB default)
 MAX_UPLOAD_SIZE=52428800
-# Allowed file extensions (comma-separated)
-ALLOWED_EXTENSIONS=png,jpg,jpeg,pdf,bmp,tiff
-# Upload directories
+ALLOWED_EXTENSIONS=png,jpg,jpeg,pdf,bmp,tiff,doc,docx,ppt,pptx
 UPLOAD_DIR=./uploads
 TEMP_DIR=./uploads/temp
 PROCESSED_DIR=./uploads/processed
 IMAGES_DIR=./uploads/images
 
 # ===== Export Configuration =====
-# Storage directories
 STORAGE_DIR=./storage
 MARKDOWN_DIR=./storage/markdown
 JSON_DIR=./storage/json
 EXPORTS_DIR=./storage/exports
 
 # ===== PDF Generation Configuration =====
-# Pandoc path (auto-detected if installed via brew)
-PANDOC_PATH=/opt/homebrew/bin/pandoc
-# WeasyPrint font directory
-FONT_DIR=/System/Library/Fonts
-# Default PDF page size
+# Linux: /usr/bin/pandoc, macOS: /opt/homebrew/bin/pandoc
+PANDOC_PATH=/usr/bin/pandoc
+# Linux: /usr/share/fonts, macOS: /System/Library/Fonts
+FONT_DIR=/usr/share/fonts
 PDF_PAGE_SIZE=A4
-# Default PDF margins (mm)
 PDF_MARGIN_TOP=20
 PDF_MARGIN_BOTTOM=20
 PDF_MARGIN_LEFT=20
 PDF_MARGIN_RIGHT=20
 
-# ===== Translation Configuration (Reserved) =====
-# Enable translation feature (reserved for future)
-ENABLE_TRANSLATION=false
-# Translation engine: offline (argostranslate) or api (future)
-TRANSLATION_ENGINE=offline
-# Argostranslate models directory
-ARGOSTRANSLATE_MODELS_DIR=./models/argostranslate
+# ===== Translation Configuration (DIFY API) =====
+# Enable translation feature
+ENABLE_TRANSLATION=true
+# DIFY API endpoint
+DIFY_API_URL=https://your-dify-instance.example.com
+# DIFY API key (get from DIFY dashboard)
+DIFY_API_KEY=your-dify-api-key
 
 # ===== Background Tasks Configuration =====
-# Task queue type: memory (default) or redis (future)
 TASK_QUEUE_TYPE=memory
-# Redis URL (if using redis)
 # REDIS_URL=redis://localhost:6379/0
 
 # ===== CORS Configuration =====
-# Allowed origins (comma-separated, * for all)
-CORS_ORIGINS=http://localhost:12011,http://127.0.0.1:12011
+CORS_ORIGINS=http://localhost:5173,http://127.0.0.1:5173
 
 # ===== Logging Configuration =====
 LOG_LEVEL=INFO