Add non-regression test for TypeSpecifier trivially-true condition skip

Tests that processBooleanSureConditionalTypes correctly skips conditions
where TypeCombinator::remove() returns the same type as the input. Without
the TypeSpecifier fix, BooleanAnd creates spurious conditional expressions
(e.g. $type=non-falsy-string) because remove(non-falsy-string, 'filter')
has no effect.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

tests/PHPStan/Analyser/nsrt/bug-10055.php

@@ -30,3 +30,28 @@ function testScopeMerging(mixed $foo): void
 		assertType('1', $a);
 	}
 }
+
+/**
+ * Non-regression test for TypeSpecifier::processBooleanSureConditionalTypes
+ * skipping trivially-always-true conditions.
+ *
+ * Without the fix, the BooleanAnd handler creates spurious conditional
+ * expressions like "$type=non-falsy-string => ..." because
+ * TypeCombinator::remove(non-falsy-string, 'filter') returns
+ * non-falsy-string unchanged.
+ *
+ * @param array<string, mixed> $aggregation
+ * @param non-falsy-string $type
+ */
+function testTriviallyTrueConditionSkipped(array $aggregation, string $type): void
+{
+	if (empty($aggregation['field']) && $type !== 'filter') {
+		return;
+	}
+
+	if ($type !== 'filter') {
+		assertType("array<string, mixed>", $aggregation);
+	}
+
+	assertType('non-falsy-string', $type);
+}