feat: multi-tenant workspace isolation, RBAC, sidebar nav, billing, and Android enhancements

- Backend: workspace_id isolation for 14 model tables + safe migration/backfill
- Backend: RBAC system with 4 roles and 23 permissions, seeded on startup
- Backend: workspace admin endpoints (list/manage all workspaces)
- Backend: admin user management API (CRUD, reset password)
- Backend: billing API with subscription plans, usage tracking, rate limiting
- Backend: fix system_logs.py UNION query and wrong column references
- Backend: WebSocket JWT auth and workspace enforcement
- Frontend: sidebar navigation replacing top dropdown menu
- Frontend: user management page (Users.vue) for admins
- Frontend: enhanced Workspaces.vue with admin table view
- Frontend: workspace RBAC computed properties in user store
- Android: agent marketplace, billing/subscription UI, onboarding wizard
- Android: phone login, analytics tracker, crash handler, network diagnostics
- Android: splash screen, encrypted token storage, app update enhancements
- Docs: multi-tenant RBAC guide with 8 sections and role-permission matrix

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

backend/app/models/agent_execution_log.py

@@ -2,7 +2,7 @@
 Agent 执行日志模型 — 结构化记录每次 Agent 执行的完整信息
 用于知识自进化系统的数据基础
 """
-from sqlalchemy import Column, String, Text, Integer, DateTime, JSON, Float, Boolean
+from sqlalchemy import Column, String, Text, Integer, DateTime, JSON, Float, Boolean, ForeignKey
 from sqlalchemy.dialects.mysql import CHAR
 from app.core.database import Base
 import uuid
@@ -20,6 +20,7 @@ class AgentExecutionLog(Base):
     task_id = Column(String(36), nullable=True, index=True, comment="关联 Task ID")
     user_id = Column(String(36), nullable=True, index=True, comment="用户 ID")
     session_id = Column(String(100), nullable=True, comment="会话标识")
+    workspace_id = Column(CHAR(36), ForeignKey("workspaces.id"), nullable=True, index=True, comment="工作区ID")
 
     # 输入/输出
     input_text = Column(Text, nullable=True, comment="用户输入文本")