fix(saham): add 30 degrees when the third operand misses the B-to-A arc

Upstream ce9fed15. The exception now tests C on the forward arc from B to A, in both the value and the trace. BUG-1387.

Co-Authored-By: Grok (agent loop)
Co-authored-by: Cursor <cursoragent@cursor.com>

references/saham_rules.json

@@ -46,6 +46,6 @@
     }
   },
   "exception_rules": {
-    "add_30_degrees": "If the Ascendant does not fall between the first and the second point in the zodiacal order, add 30 degrees (1 sign) to the final result."
+    "add_30_degrees": "For A - B + C, add 30 degrees when C does not lie on the forward zodiacal arc from B to A. PVR Integrated Approach section 28.8.1, source page 394."
   }
 }