feat: invoices — patient billing with installments + PDF export

Backend (new `invoice` RBAC resource, granted to clinicians + reception):
- invoices table (line items + installments as JSONB), types, zod validation,
  service (CRUD + splitIntoInstallments + auto invoice numbers), org-scoped
  REST routes mounted at /api/invoices, activity logging (migration 0015)

Frontend:
- lib/invoices.ts API client + money/date helpers
- /invoices page: list with KPIs and search, create/edit dialog (searchable
  patient combobox, inline line-item editor, live total), detail sheet to split
  a bill into equal monthly installments, delete, and Download PDF
- dependency-free PDF via a print-styled window (browser "Save as PDF")
- sidebar "Invoices" entry under the Patients group; "Added by AI" badge honored

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

backend/src/lib/access.ts

@@ -17,6 +17,7 @@ export const statements = {
   patient: ["read", "write", "delete"],
   appointment: ["read", "write", "delete"],
   prescription: ["read", "write", "delete"],
+  invoice: ["read", "write", "delete"],
   inventory: ["read", "write", "delete"],
   task: ["read", "write", "delete"],
   lab: ["read", "write"],
@@ -40,6 +41,7 @@ export const owner = ac.newRole({
   patient: ["read", "write", "delete"],
   appointment: ["read", "write", "delete"],
   prescription: ["read", "write", "delete"],
+  invoice: ["read", "write", "delete"],
   inventory: ["read", "write", "delete"],
   task: ["read", "write", "delete"],
   lab: ["read", "write"],
@@ -50,6 +52,7 @@ export const admin = ac.newRole({
   patient: ["read", "write", "delete"],
   appointment: ["read", "write", "delete"],
   prescription: ["read", "write", "delete"],
+  invoice: ["read", "write", "delete"],
   inventory: ["read", "write", "delete"],
   task: ["read", "write", "delete"],
   lab: ["read", "write"],
@@ -61,6 +64,7 @@ export const member = ac.newRole({
   patient: ["read", "write"],
   appointment: ["read", "write", "delete"],
   prescription: ["read", "write", "delete"],
+  invoice: ["read", "write", "delete"],
   inventory: ["read", "write", "delete"],
   task: ["read", "write", "delete"],
   lab: ["read", "write"],
@@ -74,6 +78,7 @@ export const doctor = ac.newRole({
   patient: ["read", "write"],
   appointment: ["read", "write", "delete"],
   prescription: ["read", "write", "delete"],
+  invoice: ["read", "write", "delete"],
   inventory: ["read", "write", "delete"],
   task: ["read", "write", "delete"],
   lab: ["read", "write"],
@@ -88,6 +93,7 @@ export const reception = ac.newRole({
   ...memberAc.statements,
   patient: ["read", "write"],
   appointment: ["read", "write", "delete"],
+  invoice: ["read", "write", "delete"],
   task: ["read", "write"],
 });
 

backend/src/lib/invoice-validation.ts

@@ -0,0 +1,41 @@
+import { z } from "zod";
+
+import { initialsFromName } from "./initials.js";
+
+const isoDate = z.string().regex(/^\d{4}-\d{2}-\d{2}$/, "Date must be YYYY-MM-DD.");
+
+export const invoiceLineItemSchema = z.object({
+  description: z.string().trim().min(1, "Description is required.").max(300),
+  quantity: z.coerce.number().min(0).max(100_000).default(1),
+  unitPrice: z.coerce.number().min(0).max(10_000_000).default(0),
+});
+
+export const invoiceInstallmentSchema = z.object({
+  label: z.string().trim().max(120).default(""),
+  amount: z.coerce.number().min(0).max(10_000_000).default(0),
+  dueAt: isoDate.nullable().default(null),
+  paid: z.boolean().default(false),
+});
+
+// Payload accepted by POST/PUT /api/invoices. `number` and `issuedAt` are filled
+// server-side on create when omitted; initials are derived from the name.
+export const invoiceInputSchema = z
+  .object({
+    fileNumber: z.string().trim().default(""),
+    name: z.string().trim().min(1, "Patient name is required.").max(200),
+    initials: z.string().trim().max(4).default(""),
+    number: z.string().trim().max(60).optional(),
+    issuedAt: isoDate.optional(),
+    dueAt: isoDate.nullish(),
+    status: z.enum(["draft", "sent", "paid", "void"]).default("draft"),
+    lineItems: z.array(invoiceLineItemSchema).default([]),
+    installments: z.array(invoiceInstallmentSchema).default([]),
+    notes: z.string().max(5000).nullish(),
+    source: z.enum(["manual", "ai"]).default("manual"),
+  })
+  .transform((v) => ({
+    ...v,
+    initials: v.initials || initialsFromName(v.name),
+  }));
+
+export type InvoiceInput = z.infer<typeof invoiceInputSchema>;