[dx] Deprecate CombineIfRector

Merging nested ifs can create much less readable code and depends on context. Replace the body with a deprecation message, remove its tests, and unregister it from the if set. Skip the type-perfect narrowing of the generic CommentsMerger::keepComments(), which only appears because this rule stopped calling it.

Claude-Session: https://claude.ai/code/session_012HQ19gVsT8wVkekuVqVXGx

Author: TomasVotruba

config/set/if.php

@@ -2,15 +2,13 @@
 
 declare(strict_types=1);
 
-use Rector\CodeQuality\Rector\If_\CombineIfRector;
 use Rector\CodeQuality\Rector\If_\ExplicitBoolCompareRector;
 use Rector\CodeQuality\Rector\If_\SimplifyIfElseToTernaryRector;
 use Rector\Config\RectorConfig;
 
 return static function (RectorConfig $rectorConfig): void {
     $rectorConfig->rules([
         ExplicitBoolCompareRector::class,
-        CombineIfRector::class,
         SimplifyIfElseToTernaryRector::class,
     ]);
 };

phpstan.neon

@@ -65,6 +65,11 @@ parameters:
         constants: true
 
     ignoreErrors:
+        # keepComments() is a generic helper; do not narrow it after the deprecated CombineIfRector stopped calling it
+        -
+            identifier: typePerfect.narrowPublicClassMethodParamType
+            path: src/BetterPhpDocParser/Comment/CommentsMerger.php
+
         # the deprecated set objects are still resolved internally, until every extension bonds its rules
         -
             message: '#deprecated (class|interface) Rector\\(Set|Bridge)\\#'