fix: allow claims without appointment + support post/core multi-tooth input

- Make appointmentId nullable/optional in Prisma Zod schema via @zod rich
  comment so claims can be submitted without an existing appointment
- Convert undefined appointmentId to null in all claim form handlers and
  the backend claim creation endpoint
- Add AI classifier rule for expanding one procedure across multiple
  comma-separated tooth numbers (e.g. "post/core on #23, 24, 25, 26")
- Add "post/core" (slash) alias to CDT lookup maps

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

apps/Backend/src/routes/claims.ts

@@ -1152,7 +1152,7 @@ router.post("/", async (req: Request, res: Response): Promise<any> => {
     // Strip unknown keys so strict() doesn't reject any extra properties the frontend may send
     const parsedClaim = (ExtendedClaimSchema as unknown as z.ZodObject<any>).strip().parse({
       patientId: req.body.patientId,
-      appointmentId: req.body.appointmentId,
+      appointmentId: req.body.appointmentId ?? null,
       staffId: req.body.staffId,
       patientName: req.body.patientName,
       memberId: req.body.memberId,