feat(models): 组织、用户、角色、客户、会话与消息模型

按组织边界定义数据关系，补齐仓储层与通用工具，迁移脚本可重复执行。

backend/app/models/mcp_tool.py

@@ -0,0 +1,74 @@
+"""
+Copyright 2024-2026 ReplyPier
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+"""
+
+from sqlalchemy import Column, Integer, String, DateTime, ForeignKey, func, Enum as SQLEnum, Text, Boolean
+from sqlalchemy.orm import relationship
+from app.database import Base
+import enum
+from sqlalchemy.dialects.postgresql import UUID, JSON
+
+class MCPTransportType(str, enum.Enum):
+    STDIO = "stdio"
+    SSE = "sse"
+    HTTP = "http"
+
+
+class MCPTool(Base):
+    __tablename__ = "mcp_tools"
+
+    id = Column(Integer, primary_key=True, index=True)
+    name = Column(String, nullable=False)  # Display name for the MCP server
+    description = Column(Text)  # Optional description of what this MCP server does
+    # What this source holds and how to query it. Reaches the model as agno
+    # per-toolkit instructions, in the system prompt — unlike `description`,
+    # which is a preset-populated UI subtitle the model never sees.
+    usage_guidance = Column(Text)
+    transport_type = Column(SQLEnum(MCPTransportType), nullable=False)
+    enabled = Column(Boolean, default=True, nullable=False)
+    
+    # For STDIO transport
+    command = Column(String)  # e.g., "npx", "uvx", "node"
+    args = Column(JSON)  # List of arguments, e.g., ["-y", "@modelcontextprotocol/server-filesystem"]
+    env_vars = Column(JSON)  # Environment variables as key-value pairs
+    
+    # For SSE/HTTP transports
+    url = Column(String)  # Server URL
+    headers = Column(JSON)  # HTTP headers as key-value pairs
+    timeout = Column(Integer)  # Connection timeout in seconds
+    sse_read_timeout = Column(Integer)  # SSE read timeout in seconds
+    terminate_on_close = Column(Boolean, default=True)  # For HTTP transport
+    
+    # Relationships
+    organization_id = Column(UUID(as_uuid=True), ForeignKey("organizations.id"), nullable=False)
+    created_at = Column(DateTime, server_default=func.now())
+    updated_at = Column(DateTime, server_default=func.now(), onupdate=func.now())
+
+    # Relationships
+    organization = relationship("Organization", back_populates="mcp_tools")
+    agent_links = relationship("MCPToolToAgent", back_populates="mcp_tool", cascade="all, delete-orphan")
+
+
+class MCPToolToAgent(Base):
+    __tablename__ = "mcp_tool_to_agent"
+
+    id = Column(Integer, primary_key=True, index=True)
+    mcp_tool_id = Column(Integer, ForeignKey("mcp_tools.id"), nullable=False)
+    agent_id = Column(UUID(as_uuid=True), ForeignKey("agents.id"), nullable=False)
+    created_at = Column(DateTime, server_default=func.now())
+
+    # Relationships
+    mcp_tool = relationship("MCPTool", back_populates="agent_links")
+    agent = relationship("Agent", back_populates="mcp_tool_links")