feat: implement ERP AI Assistant Phase 1

Backend (FastAPI + SQLAlchemy + Claude API + RAG):
- Config management with Pydantic v2
- Database engine with connection pooling and SQL injection prevention
- AI engine with Claude API integration (support custom base URL)
- RAG engine with ChromaDB and sentence-transformers
- Requirement analysis service
- Config generation service
- Executor engine with SQL validation
- REST API endpoints: /analyze, /generate, /execute

Frontend (Vue 3 + Element Plus + Pinia):
- Complete 3-step workflow: analyze → generate → execute
- Step indicator with progress visualization
- Analysis result display with field table
- SQL preview with monospace font
- Execute confirmation dialog with safety warning
- Execution result display
- State management with Pinia
- API service integration

Security:
- SQL injection prevention with parameterized queries
- Dangerous SQL operation blocking
- Database password URL encoding
- Transaction auto-rollback
- Pydantic config validation

Features:
- Natural language requirement analysis
- Automated SQL configuration generation
- Safe execution with human review
- LAN access support
- Custom Claude API endpoint support

Documentation:
- README with quick start guide
- Quick start guide
- LAN access configuration
- Dependency fixes guide
- Claude API configuration
- Git operation guide
- Implementation report

Dependencies fixed:
- numpy<2.0.0 for chromadb compatibility
- sentence-transformers==2.7.0 for huggingface_hub compatibility

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/config.py

@@ -0,0 +1,67 @@
+from pydantic_settings import BaseSettings
+from pydantic import ConfigDict, field_validator
+from functools import lru_cache
+from urllib.parse import quote_plus
+
+
+class Settings(BaseSettings):
+    # Application
+    APP_NAME: str = "ERP AI Assistant"
+    APP_ENV: str = "development"
+    DEBUG: bool = True
+    SECRET_KEY: str
+
+    # Database
+    DB_DRIVER: str
+    DB_SERVER: str
+    DB_PORT: int = 1433
+    DB_NAME: str
+    DB_USER: str
+    DB_PASSWORD: str
+
+    # Claude API
+    ANTHROPIC_API_KEY: str
+    ANTHROPIC_BASE_URL: str | None = None  # Optional custom base URL for proxy/self-hosted
+    CLAUDE_MODEL: str = "claude-sonnet-4-6"
+    CLAUDE_MAX_TOKENS: int = 8192
+    CLAUDE_TEMPERATURE: float = 0.7
+
+    # Knowledge Base
+    KNOWLEDGE_BASE_PATH: str = "./knowledge_base"
+    CHROMA_DB_PATH: str = "./knowledge_base/chroma_db"
+    EMBEDDING_MODEL: str = "all-MiniLM-L6-v2"
+    CHUNK_SIZE: int = 500
+    CHUNK_OVERLAP: int = 50
+
+    @property
+    def DATABASE_URL(self) -> str:
+        """构建数据库连接 URL（密码安全编码）"""
+        password = quote_plus(self.DB_PASSWORD)
+        return (
+            f"mssql+pyodbc://{self.DB_USER}:{password}"
+            f"@{self.DB_SERVER}:{self.DB_PORT}/{self.DB_NAME}"
+            f"?driver={quote_plus(self.DB_DRIVER)}"
+        )
+
+    @field_validator('CLAUDE_TEMPERATURE')
+    @classmethod
+    def validate_temperature(cls, v):
+        if not 0 <= v <= 2:
+            raise ValueError('CLAUDE_TEMPERATURE must be between 0 and 2')
+        return v
+
+    @field_validator('CHUNK_OVERLAP')
+    @classmethod
+    def validate_chunk_overlap(cls, v, info):
+        chunk_size = info.data.get('CHUNK_SIZE', 500)
+        if v >= chunk_size:
+            raise ValueError('CHUNK_OVERLAP must be less than CHUNK_SIZE')
+        return v
+
+    model_config = ConfigDict(env_file=".env", case_sensitive=True)
+
+
+@lru_cache()
+def get_settings() -> Settings:
+    """获取配置单例"""
+    return Settings()