fix: bound Budhaditya yoga under combustion (upstream 994638f0, Budha-Aditya part only)

A combust Mercury keeps the Budha-Aditya formation visible but downgrades it
to conditional. Upstream's other card-gating fields in the same hunk come
from separate commits and are not taken. TASK-upstream-sync5-20261002 U7.

(cherry picked from commit 994638f0)

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N4f2nya58RoRu4yEmJgRGE

tests/test_budhaditya_combustion_gate.py

@@ -0,0 +1,29 @@
+from scripts.yoga_engine import YogaEngine
+
+
+def test_budhaditya_with_combust_mercury_is_conditional():
+    engine = YogaEngine('references/yoga_rules.json')
+    planets = {
+        'Sun': {'sign': 'Aries', 'house': 1},
+        'Mercury': {'sign': 'Aries', 'house': 1, 'combust': True},
+    }
+    rows = [row for row in engine.detect(planets, 'Aries') if row['rule_id'] == 'budhaditya_yoga']
+    assert len(rows) == 1
+    row = rows[0]
+    assert row['condition_status'] == 'combustion_requires_review'
+    assert row['effects'] == []
+    assert row['traditional_effects']
+    assert row['strength'] == 'conditional'
+    assert row['combustion_witness']['planet'] == 'Mercury'
+
+
+def test_budhaditya_without_combustion_keeps_traditional_effects():
+    engine = YogaEngine('references/yoga_rules.json')
+    planets = {
+        'Sun': {'sign': 'Aries', 'house': 1},
+        'Mercury': {'sign': 'Aries', 'house': 1, 'combust': False},
+    }
+    rows = [row for row in engine.detect(planets, 'Aries') if row['rule_id'] == 'budhaditya_yoga']
+    assert len(rows) == 1
+    assert rows[0]['effects']
+    assert 'combustion_witness' not in rows[0]