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

crates/erp-plugin/Cargo.toml

@@ -0,0 +1,30 @@
+[package]
+name = "erp-plugin"
+version = "0.1.0"
+edition = "2024"
+description = "ERP WASM 插件运行时 — 生产级 Host API"
+
+[dependencies]
+wasmtime = "43"
+wasmtime-wasi = "43"
+erp-core = { workspace = true }
+tokio = { workspace = true }
+serde = { workspace = true }
+serde_json = { workspace = true }
+sea-orm = { workspace = true }
+uuid = { workspace = true }
+chrono = { workspace = true }
+tracing = { workspace = true }
+thiserror = { workspace = true }
+dashmap = "6"
+toml = "0.8"
+axum = { workspace = true }
+utoipa = { workspace = true }
+async-trait = { workspace = true }
+sha2 = { workspace = true }
+base64 = "0.22"
+moka = { version = "0.12", features = ["sync"] }
+regex = "1"
+csv = { workspace = true }
+rust_xlsxwriter = { workspace = true }
+validator = { workspace = true }