feat: HL7/FHIR, e-prescribing & insurance claims integrations

Real, standards-compliant integration clients that the clinic points at
its own (sandbox or production) endpoints — no mock data.

backend:
- `integrations` table (per org+type) storing endpoint + encrypted
  credentials (reusing the AI-key crypto) + status; Drizzle migration
- services/integrations:
  - fhir.ts — FHIR R4 REST client (pull lab Observations → patient
    record), HL7 v2 ORU parsing, capability-statement connection test
  - eprescribe.ts — NCPDP SCRIPT NewRx message build + transmit
  - claims.ts — X12 837P claim generation + 835 remittance parsing
- `/api/integrations` route: config GET/PUT (owner/admin), connection
  test, and the FHIR sync / HL7 ingest / e-Rx send / claim submit actions,
  RBAC-gated (lab/patient, prescription, invoice)

frontend:
- lib/integrations.ts client
- Settings → Integrations tab to configure endpoints/credentials/enable
  + test each integration
- on-page actions, shown only when the integration is enabled:
  Lab page → FHIR "Sync results" card; prescription sheet → "Send to
  pharmacy"; invoice sheet → "Submit claim"

Production e-Rx/claims routing requires the clinic's own Surescripts /
clearinghouse credentials; the code transmits real messages once supplied.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/src/index.ts

@@ -16,6 +16,7 @@ import { appointmentsRouter } from "./routes/appointments.js";
 import { chatRouter } from "./routes/chat.js";
 import { conversationsRouter } from "./routes/conversations.js";
 import { dispensesRouter } from "./routes/dispenses.js";
+import { integrationsRouter } from "./routes/integrations.js";
 import { inventoryRouter } from "./routes/inventory.js";
 import { invoicesRouter } from "./routes/invoices.js";
 import { notesRouter } from "./routes/notes.js";
@@ -80,6 +81,7 @@ app.use("/api/notifications", notificationsRouter);
 app.use("/api/settings", settingsRouter);
 app.use("/api/ai", aiRouter);
 app.use("/api/chat", chatRouter);
+app.use("/api/integrations", integrationsRouter);
 
 app.use(notFound);
 app.use(errorHandler);
@@ -107,4 +109,5 @@ server.listen(env.PORT, () => {
   console.log(`  • settings: /api/settings`);
   console.log(`  • ai:       /api/ai  (config + import)`);
   console.log(`  • chat:     /api/chat  (LLM agent)`);
+  console.log(`  • integr.:  /api/integrations  (FHIR / e-Rx / claims)`);
 });