feat(package): session packages backed by a credit ledger

"Six laser sessions" is the common case in an aesthetics clinic: the patient
pays once and books the sessions later.

Credit is a ledger, not a counter. No table has a remaining/used_count column
and a schema test enforces that — the balance is always SUM(delta) over
append-only rows, so every number a patient sees has a full history behind it.
Corrections are new rows, never edits.

- purchase / consume / refund / adjustment / expiry, each with a reason, an
  author and the appointment it belongs to
- consume happens in confirm(), never in quote(): if the preview consumed, a
  page refresh would cost the patient a session
- cancelling adds a refund row; the consume row stays
- FIFO across a patient's packages — the oldest is closest to expiring
- an empty package is not an error, it just does not apply and the patient pays
- adjust/expire need a doctor or clinic role, and adjust always needs a reason
- app:package:expire writes the closing row so "where did my 3 sessions go?"
  always has an answer

Consume takes a pessimistic lock on the one package row. That is the opposite
of task 07's slot buckets, and docs/api/package.md carries the table explaining
why, so nobody unifies them later.

Idempotency checks for an existing consume row before inserting rather than
catching the unique violation: in Doctrine that exception closes the
EntityManager and burns the rest of the request. The unique key stays as the
last line of defence.

Admin: PackagesPage, a packages tab on the patient record, and a ledger page
whose running-balance column shows where the final number came from.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

assets/admin/types/index.ts

@@ -1204,3 +1204,50 @@ export interface PolicySimulationRun {
     rows: SimulationRow[];
     warning: string | null;
 }
+
+// ── پکیج و اعتبار جلسات (تسک ۱۱) ─────────────────────────────────────────────
+
+export interface PackageDefinition {
+    uuid: string;
+    name: string;
+    session_count: number;
+    price_rials: number;
+    /** `null` یعنی بی‌پایان */
+    validity_days: number | null;
+    active: boolean;
+    services: { uuid: string; name: string }[];
+    created_at: number;
+}
+
+export interface PatientPackage {
+    uuid: string;
+    package_uuid: string;
+    package_name: string;
+    patient_uuid: string;
+    session_count: number;
+    price_paid_rials: number;
+    purchased_at: number;
+    valid_to: number | null;
+    expired: boolean;
+    /** همیشه از جمع دفتر می‌آید — هیچ ستونی در دیتابیس نیست */
+    balance: number;
+}
+
+export interface CreditLedgerRow {
+    uuid: string;
+    kind: 'purchase' | 'consume' | 'refund' | 'adjustment' | 'expiry';
+    delta: number;
+    appointment_uuid: string | null;
+    service_uuid: string | null;
+    service_name: string | null;
+    reason: string | null;
+    created_by: string | null;
+    created_at: number;
+    /** در UI محاسبه‌شده نیست — سرور همان جمع تجمعی را می‌دهد */
+    running_balance: number;
+}
+
+export interface CreditLedger {
+    package: PatientPackage;
+    rows: CreditLedgerRow[];
+}