feat: AI-added records save with placeholders + "Added by AI" provenance

Stop blocking AI imports/proposals on missing non-critical fields. Records
the chat agent drafts now save with safe placeholders, auto-generated file
numbers, and a source="ai" marker that surfaces an "Added by AI" badge so a
clinician can review/edit them later.

Backend:
- add `source` (manual|ai) column to patients/appointments/prescriptions
  (migration 0014) + canonical types, services, validation schemas
- relax patient/appointment validation: empty file number allowed, demographic
  + type/provider/initials fall back to placeholders (initials derived from name)
- patients.generateFileNumber() auto-assigns an MRN when one is missing
- proposeAppointment accepts a name when no file number resolves; AI commits +
  /api/ai/import stamp source="ai"

Frontend:
- `source` on Appointment/Patient/Prescription types; AI commits send source="ai"
- reusable <AiBadge> shown on the Patients table/detail and prescriptions list

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

frontend/components/chat/action-preview-card.tsx

@@ -45,12 +45,20 @@ function summarize(data: ActionPreviewData): string[] {
 }
 
 async function commit(data: ActionPreviewData): Promise<void> {
+  // Stamp provenance so the committed record is flagged "Added by AI" and shows
+  // up for review/editing on the relevant page.
   if (data.kind === "appointment") {
-    await createAppointment(data.record as AppointmentInput);
+    await createAppointment({
+      ...(data.record as AppointmentInput),
+      source: "ai",
+    });
   } else if (data.kind === "task") {
     await createTask(data.record as TaskInput);
   } else {
-    await createPrescription(data.record as PrescriptionInput);
+    await createPrescription({
+      ...(data.record as PrescriptionInput),
+      source: "ai",
+    });
   }
 }