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/PatientConversationCreateNestedOneWithoutPatientInput.schema.ts

@@ -0,0 +1,14 @@
+import * as z from 'zod';
+import type { Prisma } from '../../../generated/prisma';
+import { PatientConversationCreateWithoutPatientInputObjectSchema as PatientConversationCreateWithoutPatientInputObjectSchema } from './PatientConversationCreateWithoutPatientInput.schema';
+import { PatientConversationUncheckedCreateWithoutPatientInputObjectSchema as PatientConversationUncheckedCreateWithoutPatientInputObjectSchema } from './PatientConversationUncheckedCreateWithoutPatientInput.schema';
+import { PatientConversationCreateOrConnectWithoutPatientInputObjectSchema as PatientConversationCreateOrConnectWithoutPatientInputObjectSchema } from './PatientConversationCreateOrConnectWithoutPatientInput.schema';
+import { PatientConversationWhereUniqueInputObjectSchema as PatientConversationWhereUniqueInputObjectSchema } from './PatientConversationWhereUniqueInput.schema'
+
+const makeSchema = () => z.object({
+  create: z.union([z.lazy(() => PatientConversationCreateWithoutPatientInputObjectSchema), z.lazy(() => PatientConversationUncheckedCreateWithoutPatientInputObjectSchema)]).optional(),
+  connectOrCreate: z.lazy(() => PatientConversationCreateOrConnectWithoutPatientInputObjectSchema).optional(),
+  connect: z.lazy(() => PatientConversationWhereUniqueInputObjectSchema).optional()
+}).strict();
+export const PatientConversationCreateNestedOneWithoutPatientInputObjectSchema: z.ZodType<Prisma.PatientConversationCreateNestedOneWithoutPatientInput> = makeSchema() as unknown as z.ZodType<Prisma.PatientConversationCreateNestedOneWithoutPatientInput>;
+export const PatientConversationCreateNestedOneWithoutPatientInputObjectZodSchema = makeSchema();