chore: remove AI dev files from repo and clean up env config

- Remove .claude/, openspec/, AGENTS.md, CLAUDE.md from git tracking
- Simplify .env.example: remove unused path configs (use config.py defaults)
- Clean up .env for production: remove hardcoded secrets, use env var substitution
- Path configs now use sensible defaults from backend/app/core/config.py:
  - uploads -> backend/uploads/
  - storage -> backend/storage/
  - results -> backend/storage/results/

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

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

.env

@@ -1,82 +1,49 @@
-# Tool_OCR - Docker Environment Configuration
-# Copy this file to .env when deploying with Docker
+# Tool_OCR - Production/Docker Environment Configuration
+# For local development, copy .env.example to .env.local and configure there
+#
+# This file is for Docker deployment or production use.
+# Sensitive values should be set via environment variables or secrets management.
 
 # ===== Database Configuration =====
-MYSQL_HOST=mysql.theaken.com
-MYSQL_PORT=33306
-MYSQL_USER=A060
-MYSQL_PASSWORD=WLeSCi0yhtc7
-MYSQL_DATABASE=db_A060
+# Set these via Docker secrets or environment variables in production
+MYSQL_HOST=${MYSQL_HOST:-localhost}
+MYSQL_PORT=${MYSQL_PORT:-3306}
+MYSQL_USER=${MYSQL_USER:-}
+MYSQL_PASSWORD=${MYSQL_PASSWORD:-}
+MYSQL_DATABASE=${MYSQL_DATABASE:-}
 
 # ===== Application Configuration =====
-# External port (exposed to host)
+# Production port (different from development)
 FRONTEND_PORT=12010
+BACKEND_PORT=8000
 
-# Security (IMPORTANT: Change SECRET_KEY in production!)
-SECRET_KEY=your-secret-key-here-please-change-this-to-random-string
+# Security - MUST be set via environment variable in production
+SECRET_KEY=${SECRET_KEY:-change-this-in-production}
 ALGORITHM=HS256
 ACCESS_TOKEN_EXPIRE_MINUTES=1440
 
+# ===== External Authentication Configuration =====
+EXTERNAL_AUTH_API_URL=${EXTERNAL_AUTH_API_URL:-https://your-auth-api.example.com}
+EXTERNAL_AUTH_ENDPOINT=/api/auth/login
+EXTERNAL_AUTH_TIMEOUT=30
+
 # ===== OCR Configuration =====
-# PaddleOCR model directory (inside container)
-PADDLEOCR_MODEL_DIR=/app/backend/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
 
-# ===== File Upload Configuration =====
-# Maximum file size in bytes (50MB default)
+# ===== File Configuration =====
 MAX_UPLOAD_SIZE=52428800
-# Allowed file extensions (comma-separated)
 ALLOWED_EXTENSIONS=png,jpg,jpeg,pdf,bmp,tiff,doc,docx,ppt,pptx
-# Upload directories (inside container)
-UPLOAD_DIR=/app/backend/uploads
-TEMP_DIR=/app/backend/uploads/temp
-PROCESSED_DIR=/app/backend/uploads/processed
-IMAGES_DIR=/app/backend/uploads/images
 
-# ===== Export Configuration =====
-# Storage directories (inside container)
-STORAGE_DIR=/app/backend/storage
-MARKDOWN_DIR=/app/backend/storage/markdown
-JSON_DIR=/app/backend/storage/json
-EXPORTS_DIR=/app/backend/storage/exports
-
-# ===== PDF Generation Configuration =====
-# Pandoc path (inside container)
-PANDOC_PATH=/usr/bin/pandoc
-# Font directory (inside container)
-FONT_DIR=/usr/share/fonts
-# Default PDF page size
-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 (inside container)
-ARGOSTRANSLATE_MODELS_DIR=/app/backend/models/argostranslate
-
-# ===== 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
+# ===== Translation Configuration (DIFY API) =====
+ENABLE_TRANSLATION=${ENABLE_TRANSLATION:-false}
+DIFY_BASE_URL=${DIFY_BASE_URL:-}
+DIFY_API_KEY=${DIFY_API_KEY:-}
+DIFY_TIMEOUT=120.0
 
 # ===== CORS Configuration =====
-# Allowed origins (comma-separated, * for all)
-# For Docker, use the external URL
 CORS_ORIGINS=http://localhost:12010,http://127.0.0.1:12010
 
 # ===== Logging Configuration =====
 LOG_LEVEL=INFO
-LOG_FILE=/app/backend/logs/app.log