fix(sqlite): Convert boolean literals (true/false) to bool type

Previously, SQLite boolean literals like `SELECT true` were incorrectly
converted to int64 type, while PostgreSQL correctly returned bool.

The ANTLR parser provides TRUE_() and FALSE_() tokens, but these were
originally implemented to return Integer in PR #1447 (2022-02-19) without
specific reasoning, likely because SQLite internally uses integers (1/0)
for boolean values.

This fix changes the TRUE_()/FALSE_() handling to return ast.Boolean
instead of ast.Integer, aligning SQLite's behavior with PostgreSQL
and providing a more type-safe interface.

Test results:
- SELECT true/false → bool (was int64)
- SELECT TRUE/FALSE → bool (was int64)
- SELECT 1 → int64 (unchanged)

Added test: internal/endtoend/testdata/select_true_literal/sqlite/

Author: kitagry

internal/endtoend/testdata/select_true_literal/sqlite/db/db.go

@@ -0,0 +1,14 @@
+-- name: SelectTrue :one
+SELECT true;
+
+-- name: SelectFalse :one
+SELECT false;
+
+-- name: SelectTrueWithAlias :one
+SELECT true AS is_active;
+
+-- name: SelectMultipleBooleans :one
+SELECT true AS col_a, false AS col_b, true AS col_c;
+
+-- name: SelectOne :one
+SELECT 1;

internal/endtoend/testdata/select_true_literal/sqlite/db/models.go

@@ -0,0 +1,10 @@
+{
+  "version": "1",
+  "packages": [
+    {
+      "path": "db",
+      "engine": "sqlite",
+      "queries": "query.sql"
+    }
+  ]
+}

internal/endtoend/testdata/select_true_literal/sqlite/db/query.sql.go

@@ -752,13 +752,8 @@ func (c *cc) convertLiteral(n *parser.Expr_literalContext) ast.Node {
 		}
 
 		if literal.TRUE_() != nil || literal.FALSE_() != nil {
-			var i int64
-			if literal.TRUE_() != nil {
-				i = 1
-			}
-
 			return &ast.A_Const{
-				Val:      &ast.Integer{Ival: i},
+				Val:      &ast.Boolean{Boolval: literal.TRUE_() != nil},
 				Location: n.GetStart().GetStart(),
 			}
 		}