Wrap a table-valued function in a derived table after LATERAL. Fix #1277

VisitCrossApply and VisitOuterApply already know that Firebird will not take a
bare source after LATERAL: both special-case a TableExpression and emit
(SELECT * FROM "T") AS "t". The same branch was missing for a
TableValuedFunctionExpression, so a correlated queryable function was emitted as
a bare call and the statement did not parse:

  JOIN LATERAL "GetCustomerOrderCountByYear"("c"."Id") AS "g" ON TRUE
  -> Dynamic SQL Error, Token unknown

It now emits the wrapped form, with the alias on the derived table so the rest of
the statement keeps referring to it unchanged:

  JOIN LATERAL (SELECT * FROM "GetCustomerOrderCountByYear"("c"."Id")) AS "g" ON TRUE

Argument rendering goes through the existing GenerateList helper rather than a
new loop.

UdfDbFunctionFbTests: Failed 12 -> 0, Passed 84 -> 96, Skipped 10, Total 106.

No other test moved. The whole functional suite is Passed 14167, Failed 0,
Skipped 1113, Total 15280, and FirebirdSql.EntityFrameworkCore.Firebird.Tests is
Passed 102, Failed 0. Verified against Firebird 5.0.3.

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

Author: azabluda

src/FirebirdSql.EntityFrameworkCore.Firebird/Query/Internal/FbQuerySqlGenerator.cs

@@ -298,6 +298,12 @@ protected override Expression VisitCrossApply(CrossApplyExpression crossApplyExp
 				.Append(AliasSeparator)
 				.Append(Dependencies.SqlGenerationHelper.DelimitIdentifier(table.Alias));
 		}
+		else if (crossApplyExpression.Table is TableValuedFunctionExpression function)
+		{
+			// Same for a table-valued function. The alias goes on the derived table rather than
+			// on the call, so the rest of the statement keeps referring to it unchanged.
+			GenerateLateralFunction(function);
+		}
 		else
 		{
 			Visit(crossApplyExpression.Table);
@@ -325,6 +331,12 @@ protected override Expression VisitOuterApply(OuterApplyExpression outerApplyExp
 				.Append(AliasSeparator)
 				.Append(Dependencies.SqlGenerationHelper.DelimitIdentifier(table.Alias));
 		}
+		else if (outerApplyExpression.Table is TableValuedFunctionExpression function)
+		{
+			// Same for a table-valued function. The alias goes on the derived table rather than
+			// on the call, so the rest of the statement keeps referring to it unchanged.
+			GenerateLateralFunction(function);
+		}
 		else
 		{
 			Visit(outerApplyExpression.Table);
@@ -334,6 +346,23 @@ protected override Expression VisitOuterApply(OuterApplyExpression outerApplyExp
 		return outerApplyExpression;
 	}
 
+	// Firebird will not take a bare table-valued function after LATERAL either, so it is
+	// wrapped the same way a table is: (SELECT * FROM "Func"(args)) AS "alias".
+	void GenerateLateralFunction(TableValuedFunctionExpression function)
+	{
+		Sql
+			.Append("(SELECT * FROM ")
+			.Append(Dependencies.SqlGenerationHelper.DelimitIdentifier(function.Name, function.Schema))
+			.Append("(");
+
+		GenerateList(function.Arguments, e => Visit(e));
+
+		Sql
+			.Append("))")
+			.Append(AliasSeparator)
+			.Append(Dependencies.SqlGenerationHelper.DelimitIdentifier(function.Alias));
+	}
+
 	protected override void GeneratePseudoFromClause()
 	{
 		Sql.Append(" FROM RDB$DATABASE");