fix(products): clearer error message for an FD product amount field that's too large

The FD product's exception mapper fell back to a bare "Unknown data
integrity issue with savings product." for any DB error it didn't
recognize, with no detail -- unlike its sibling class for regular Savings
products, which at least appends the underlying error. Added a specific,
actionable message for the numeric-overflow case (an amount field entered
too large for its column), and made the generic fallback include the real
detail too.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

fineract-provider/src/main/java/org/apache/fineract/portfolio/savings/service/FixedDepositProductWritePlatformServiceJpaRepositoryImpl.java

@@ -402,8 +402,13 @@ public class FixedDepositProductWritePlatformServiceJpaRepositoryImpl implements
             msg = "Savings product with short name `" + shortName + "` already exists";
             param = "shortName";
             msgArgs = new Object[] { shortName, dae };
+        } else if (checkEx.getMessage().contains("numeric field overflow")) {
+            msgCode += ".amount.too.large";
+            msg = "One of the amount fields entered is too large (Minimum/Maximum Deposit Amount or Pre-Closure Penal Interest). Please enter a realistic value and try again.";
+            msgArgs = new Object[] { dae };
         } else {
             msgCode += ".unknown.data.integrity.issue";
+            msg = "Unknown data integrity issue with savings product. Details: " + checkEx.getMessage();
             msgArgs = new Object[] { dae };
         }
         log.error("Error occured.", dae);