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-server/src/handlers/mod.rs

@@ -0,0 +1,6 @@
+pub mod analytics;
+pub mod audit_log;
+pub mod crypto_admin;
+pub mod health;
+pub mod openapi;
+pub mod upload;