feat: initialize ERP base platform (extracted from HMS)

- Stripped 11 business crates (health, ai, dialysis, plugins)
- Cleaned AppState, AppConfig, main.rs from business coupling
- Reduced migrations from 169 to 53 (base-only)
- Removed health_provider trait from erp-core
- Removed business integration tests
- Removed gateway rate limiting middleware
- Base capabilities: auth, RBAC, JWT, config, workflow, message, plugin, audit, crypto, RLS, multi-tenant

Cargo check: OK
Cargo test: OK

README.md

@@ -0,0 +1,64 @@
+# ERP Platform Base
+
+模块化商业 SaaS ERP 平台底座。
+
+## 技术栈
+
+| 层级 | 技术 |
+|------|------|
+| 后端 | Rust (Axum 0.8 + SeaORM + Tokio) |
+| 数据库 | PostgreSQL 16+ |
+| 缓存 | Redis 7+ |
+| 前端 | Vite + React 18 + TypeScript + Ant Design 5 |
+
+## 项目结构
+
+```
+erp/
+├── crates/
+│   ├── erp-core/          # 基础类型、错误、事件总线、模块 trait
+│   ├── erp-common/        # 共享工具
+│   ├── erp-auth/          # 身份与权限 (Phase 2)
+│   ├── erp-workflow/      # 工作流引擎 (Phase 4)
+│   ├── erp-message/       # 消息中心 (Phase 5)
+│   ├── erp-config/        # 系统配置 (Phase 3)
+│   └── erp-server/        # Axum 服务入口
+│       └── migration/     # SeaORM 数据库迁移
+├── apps/web/              # React SPA 前端
+├── docker/                # Docker 开发环境
+└── docs/                  # 文档
+```
+
+## 快速开始
+
+### 1. 启动基础设施
+
+```bash
+cd docker && docker compose up -d
+```
+
+### 2. 启动后端
+
+```bash
+cargo run -p erp-server
+```
+
+### 3. 启动前端
+
+```bash
+cd apps/web && pnpm install && pnpm dev
+```
+
+### 4. 访问
+
+- 前端: http://localhost:5173
+- 后端 API: http://localhost:3000
+
+## 开发命令
+
+```bash
+cargo check                        # 编译检查
+cargo test --workspace             # 运行测试
+cargo run -p erp-server            # 启动后端
+cd apps/web && pnpm dev            # 启动前端
+```