feat: AI chat system with LangGraph, multi-step patient flows, and appointment rescheduling

- Add floating chat window Hand-off to AI toggle (per-patient) and after-hours AI toggle (global)
- Add LangGraph-powered appointment reminder flow: AI introduces itself, classifies YES/NO, handles confirmation with appointment date/time
- Add multi-step rescheduling flow: ASAP vs next week, tomorrow offer, Mon/Tue/Wed picker, morning/afternoon time slot — automatically updates appointment in DB
- Add new patient / after-hours flow: new vs existing patient, dental insurance check, MassHealth Selenium eligibility check (auto-uses saved member ID + DOB for existing patients), self-pay fallback
- Add AI Chat Settings page (Settings → Advanced) with editable greeting templates and LangGraph flow diagrams for both reminder and new-patient flows
- Add Schedule a New Patient template option in chat window, starts new-patient conversation flow
- Add GET/PUT endpoints for AI handoff, after-hours handoff, and AI chat templates
- Add multilingual support (7 languages) across all AI reply nodes with LLM generation and hardcoded fallbacks
- Add pending reschedule in-memory store and conversation stage tracking across all flows

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/db/generated/prisma/index-browser.js

@@ -145,6 +145,7 @@ exports.Prisma.PatientScalarFieldEnum = {
   policyHolder: 'policyHolder',
   allergies: 'allergies',
   medicalConditions: 'medicalConditions',
+  preferredLanguage: 'preferredLanguage',
   status: 'status',
   userId: 'userId',
   createdAt: 'createdAt',
@@ -432,6 +433,7 @@ exports.Prisma.OfficeHoursScalarFieldEnum = {
 exports.Prisma.OfficeContactScalarFieldEnum = {
   id: 'id',
   userId: 'userId',
+  officeName: 'officeName',
   receptionistName: 'receptionistName',
   dentistName: 'dentistName',
   phoneNumber: 'phoneNumber',
@@ -439,6 +441,14 @@ exports.Prisma.OfficeContactScalarFieldEnum = {
   fax: 'fax'
 };
 
+exports.Prisma.InsuranceContactScalarFieldEnum = {
+  id: 'id',
+  userId: 'userId',
+  name: 'name',
+  phoneNumber: 'phoneNumber',
+  createdAt: 'createdAt'
+};
+
 exports.Prisma.ProcedureTimeslotScalarFieldEnum = {
   id: 'id',
   userId: 'userId',
@@ -591,6 +601,7 @@ exports.Prisma.ModelName = {
   AiSettings: 'AiSettings',
   OfficeHours: 'OfficeHours',
   OfficeContact: 'OfficeContact',
+  InsuranceContact: 'InsuranceContact',
   ProcedureTimeslot: 'ProcedureTimeslot'
 };