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>

docs/api/pricing.md

@@ -154,3 +154,13 @@ ddev exec php bin/phpunit tests/Pricing   # ۱۲ تست
 ```
 
 جزئیات دسته‌ها و اثرها: [policy.md](policy.md)
+
+---
+
+## پکیج
+
+`quote` یک `patient_uuid` اختیاری می‌گیرد؛ با آن، پکیج معتبرِ بیمار قیمت پایهٔ سرویس را
+می‌پوشاند و `package_will_be_consumed` روشن می‌شود. **پیش‌نمایش هرگز مصرف نمی‌کند** —
+مصرف در ثبت نهایی است.
+
+جزئیات: [package.md](package.md)