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

apps/web/src/api/ai/chat.ts

@@ -0,0 +1,118 @@
+import client from '../client';
+
+export interface ChatHistoryItem {
+  role: 'user' | 'assistant';
+  content: string;
+}
+
+export type DisplayHint =
+  | {
+      type: 'vital_card';
+      indicator_type: string;
+      values: [string, number][];
+      unit: string;
+    }
+  | {
+      type: 'lab_report_card';
+      report_date: string;
+      abnormal_count: number;
+    }
+  | {
+      type: 'action_confirm';
+      action_type: string;
+      summary: string;
+      confirm_payload: unknown;
+    }
+  | {
+      type: 'risk_alert';
+      level: string;
+      message: string;
+    }
+  | {
+      type: 'trend_chart';
+      metrics: string[];
+      period: string;
+      summary: string;
+    }
+  | {
+      type: 'insight_card';
+      title: string;
+      severity: string;
+      items: string[];
+    }
+  | {
+      type: 'patient_profile';
+      chronic_conditions: string[];
+      medication_count: number;
+    }
+  | { type: 'text' };
+
+export interface ChatResponse {
+  reply: string;
+  message_id: string;
+  iterations: number;
+  display_hints?: DisplayHint[];
+}
+
+export interface ChatSession {
+  id: string;
+  title: string | null;
+  patient_id: string | null;
+  status: string;
+  created_at: string;
+  updated_at: string;
+}
+
+export const aiChatApi = {
+  sendMessage: async (
+    message: string,
+    history: ChatHistoryItem[],
+    patientId?: string,
+    sessionId?: string
+  ): Promise<ChatResponse> => {
+    const resp = await client.post('/ai/chat', {
+      message,
+      history,
+      ...(patientId ? { patient_id: patientId } : {}),
+      ...(sessionId ? { session_id: sessionId } : {}),
+    });
+    return resp.data.data as ChatResponse;
+  },
+
+  createSession: async (
+    patientId?: string,
+    title?: string
+  ): Promise<ChatSession> => {
+    const resp = await client.post('/ai/chat/sessions', {
+      ...(patientId ? { patient_id: patientId } : {}),
+      ...(title ? { title } : {}),
+    });
+    return resp.data.data as ChatSession;
+  },
+
+  listSessions: async (): Promise<ChatSession[]> => {
+    const resp = await client.get('/ai/chat/sessions');
+    return resp.data.data as ChatSession[];
+  },
+
+  renameSession: async (
+    sessionId: string,
+    title: string
+  ): Promise<void> => {
+    await client.put(`/ai/chat/sessions/${sessionId}/rename`, { title });
+  },
+
+  closeSession: async (sessionId: string): Promise<void> => {
+    await client.post(`/ai/chat/sessions/${sessionId}/close`);
+  },
+
+  getSessionMessages: async (sessionId: string): Promise<Array<{
+    id: string;
+    role: string;
+    content: string | null;
+    created_at: string;
+  }>> => {
+    const resp = await client.get(`/ai/chat/sessions/${sessionId}/messages`);
+    return resp.data.data;
+  },
+};