Add comprehensive YAML tests for Scottish Child Payment changes

Tests verify:
- 2025 amount (£27.15/week)
- CTC no longer qualifies from 2025 (after April 2024 removal)
- CTC still qualifies in 2023 (before removal)
- WTC no longer qualifies from 2025
- Income Support still qualifies in 2025
- JSA (income-based) still qualifies in 2025
- ESA (income-related) still qualifies in 2025
- Pension Credit still qualifies in 2025

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: vahid-ahmadi

policyengine_uk/tests/policy/baseline/gov/social_security_scotland/scottish_child_payment.yaml

@@ -131,8 +131,8 @@
     # Only child_young (age 4) eligible, £20/week * 52 = £1,040
     scottish_child_payment: 1040
 
-- name: SCP for family receiving Child Tax Credit
-  period: 2024
+- name: SCP for family receiving Child Tax Credit (2023 - CTC still qualifies)
+  period: 2023
   absolute_error_margin: 10
   input:
     people:
@@ -149,8 +149,8 @@
         members: [parent, child_1]
         region: SCOTLAND
   output:
-    # £26.70/week * 52 weeks * 1 child = £1,388.40
-    scottish_child_payment: 1388
+    # £25/week * 52 weeks * 1 child = £1,300
+    scottish_child_payment: 1300
 
 - name: No SCP before Feb 2021
   period: 2020
@@ -218,3 +218,180 @@
   output:
     # £26.70/week * 52 weeks * 4 children = £5,553.60
     scottish_child_payment: 5554
+
+# New tests for 2025 amount and qualifying benefit changes
+
+- name: SCP with 2025 amount (£27.15/week)
+  period: 2025
+  absolute_error_margin: 10
+  input:
+    people:
+      parent:
+        age: 30
+      child_1:
+        age: 5
+    benunits:
+      benunit:
+        members: [parent, child_1]
+        universal_credit: 5000
+    households:
+      household:
+        members: [parent, child_1]
+        region: SCOTLAND
+  output:
+    # £27.15/week * 52 weeks * 1 child = £1,411.80
+    scottish_child_payment: 1412
+
+- name: CTC no longer qualifies from 2025 (after April 2024)
+  period: 2025
+  absolute_error_margin: 1
+  input:
+    people:
+      parent:
+        age: 30
+      child_1:
+        age: 8
+    benunits:
+      benunit:
+        members: [parent, child_1]
+        child_tax_credit: 2000
+        universal_credit: 0
+    households:
+      household:
+        members: [parent, child_1]
+        region: SCOTLAND
+  output:
+    # CTC removed as qualifying benefit from April 2024
+    scottish_child_payment: 0
+
+- name: CTC still qualifies in 2023 (before April 2024)
+  period: 2023
+  absolute_error_margin: 10
+  input:
+    people:
+      parent:
+        age: 30
+      child_1:
+        age: 8
+    benunits:
+      benunit:
+        members: [parent, child_1]
+        child_tax_credit: 2000
+        universal_credit: 0
+    households:
+      household:
+        members: [parent, child_1]
+        region: SCOTLAND
+  output:
+    # £25/week * 52 weeks * 1 child = £1,300
+    scottish_child_payment: 1300
+
+- name: WTC no longer qualifies from 2025
+  period: 2025
+  absolute_error_margin: 1
+  input:
+    people:
+      parent:
+        age: 30
+      child_1:
+        age: 8
+    benunits:
+      benunit:
+        members: [parent, child_1]
+        working_tax_credit: 2000
+        universal_credit: 0
+    households:
+      household:
+        members: [parent, child_1]
+        region: SCOTLAND
+  output:
+    # WTC removed as qualifying benefit from April 2024
+    scottish_child_payment: 0
+
+- name: Income Support still qualifies in 2025
+  period: 2025
+  absolute_error_margin: 10
+  input:
+    people:
+      parent:
+        age: 30
+      child_1:
+        age: 5
+    benunits:
+      benunit:
+        members: [parent, child_1]
+        income_support: 3000
+        universal_credit: 0
+    households:
+      household:
+        members: [parent, child_1]
+        region: SCOTLAND
+  output:
+    # £27.15/week * 52 weeks * 1 child = £1,411.80
+    scottish_child_payment: 1412
+
+- name: JSA income-based still qualifies in 2025
+  period: 2025
+  absolute_error_margin: 10
+  input:
+    people:
+      parent:
+        age: 30
+      child_1:
+        age: 5
+    benunits:
+      benunit:
+        members: [parent, child_1]
+        jsa_income: 3000
+        universal_credit: 0
+    households:
+      household:
+        members: [parent, child_1]
+        region: SCOTLAND
+  output:
+    # £27.15/week * 52 weeks * 1 child = £1,411.80
+    scottish_child_payment: 1412
+
+- name: ESA income-related still qualifies in 2025
+  period: 2025
+  absolute_error_margin: 10
+  input:
+    people:
+      parent:
+        age: 30
+      child_1:
+        age: 5
+    benunits:
+      benunit:
+        members: [parent, child_1]
+        esa_income: 4000
+        universal_credit: 0
+    households:
+      household:
+        members: [parent, child_1]
+        region: SCOTLAND
+  output:
+    # £27.15/week * 52 weeks * 1 child = £1,411.80
+    scottish_child_payment: 1412
+
+- name: Pension Credit still qualifies in 2025
+  period: 2025
+  absolute_error_margin: 10
+  input:
+    people:
+      grandparent:
+        age: 70
+      child_1:
+        age: 10
+    benunits:
+      benunit:
+        members: [grandparent, child_1]
+        pension_credit: 5000
+        universal_credit: 0
+    households:
+      household:
+        members: [grandparent, child_1]
+        region: SCOTLAND
+  output:
+    # £27.15/week * 52 weeks * 1 child = £1,411.80
+    scottish_child_payment: 1412