feat(policy): six-category policy engine wired into the booking flow

Rules become data instead of code: a clinic can say "laser under 18 requires
parental consent" without a deploy.

Engine
- Policy / PolicyVersionLog entities, closed field/operator/effect lists per
  category (PolicySchema), condition validation at write time
- PolicyResolver: priority -> specificity -> age, combining effects by
  veto / max / sum / union
- A missing fact fails its clause instead of silently passing it
- Policies are drafts until activated, and are versioned rather than edited

Wiring
- selection -> ServiceSelectionValidator
- eligibility + spacing -> BookingPolicyGuard, at hold time not confirm time
- resource + timing -> AppointmentPlanBuilder, including template-less services
- pricing -> PricingEngine, alongside (not replacing) the manual discount

The condition column is named condition_json: `condition` is a MariaDB keyword
and broke every INSERT.

Tests: 17 in tests/Policy including NoPolicyRegressionTest, which pins that a
clinic with no policies sees byte-identical output to task 08.
Docs: docs/api/policy.md (real captured JSON) + docs/architecture/policy-engine.md.

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

docs/api/clinic-services.md

@@ -504,3 +504,19 @@ override فقط وقتی اعمال می‌شود که `branch_uuid` به `valid
 ```bash
 ddev exec php bin/phpunit tests/ClinicService     # ۵۲ تست
 ```
+
+---
+
+## قوانین دستهٔ «انتخاب»
+
+`POST /api/v1/service-selection/validate` علاوه بر گروه و رابطه، ممنوعیت‌های دستهٔ
+`selection` را هم برمی‌گرداند:
+
+```json
+{ "code": "policy_forbidden", "items": ["<service-uuid>"], "message": "این خدمت موقتاً متوقف است" }
+```
+
+گروه و رابطه ساختار ثابت کاتالوگ‌اند؛ قانون چیزی است که کلینیک بدون دست زدن به کاتالوگ
+روشن و خاموش می‌کند. اجرا فقط وقتی است که `branch_uuid` بیاید — محیط از شعبه می‌آید.
+
+جزئیات: [policy.md](policy.md)