feat: persist AI conversation state in DB and fix LangGraph flow bugs

- Replace in-memory Maps in aiHandoffStore with DB-backed async functions
  using new patient_conversation table (stage + aiHandoff per patient)
- Add afterHoursEnabled to ai_settings table (persists across restarts)
- Fix runtime crash in reschedule-graph: mon/tue/wed variables were out
  of scope in the next-week fallback branch (ReferenceError)
- Wire rescheduleGreeting and generalFallback chat templates through to
  LangGraph nodes so user-configured messages take effect
- Add otherNode to reminder-graph to handle unclassified patient replies
  (e.g. "I want another appointment") and route to booking flow
- Fetch chatTemplates once per webhook request instead of per stage

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

packages/db/shared/schemas/objects/UserSelect.schema.ts

@@ -19,6 +19,7 @@ import { OfficeHoursArgsObjectSchema as OfficeHoursArgsObjectSchema } from './Of
 import { OfficeContactArgsObjectSchema as OfficeContactArgsObjectSchema } from './OfficeContactArgs.schema';
 import { ProcedureTimeslotArgsObjectSchema as ProcedureTimeslotArgsObjectSchema } from './ProcedureTimeslotArgs.schema';
 import { InsuranceContactFindManySchema as InsuranceContactFindManySchema } from '../findManyInsuranceContact.schema';
+import { PatientConversationFindManySchema as PatientConversationFindManySchema } from '../findManyPatientConversation.schema';
 import { UserCountOutputTypeArgsObjectSchema as UserCountOutputTypeArgsObjectSchema } from './UserCountOutputTypeArgs.schema'
 
 const makeSchema = () => z.object({
@@ -46,6 +47,7 @@ const makeSchema = () => z.object({
   officeContact: z.union([z.boolean(), z.lazy(() => OfficeContactArgsObjectSchema)]).optional(),
   procedureTimeslot: z.union([z.boolean(), z.lazy(() => ProcedureTimeslotArgsObjectSchema)]).optional(),
   insuranceContacts: z.union([z.boolean(), z.lazy(() => InsuranceContactFindManySchema)]).optional(),
+  patientConversations: z.union([z.boolean(), z.lazy(() => PatientConversationFindManySchema)]).optional(),
   _count: z.union([z.boolean(), z.lazy(() => UserCountOutputTypeArgsObjectSchema)]).optional()
 }).strict();
 export const UserSelectObjectSchema: z.ZodType<Prisma.UserSelect> = makeSchema() as unknown as z.ZodType<Prisma.UserSelect>;