refactor: 型システム的に意味のないテストケースを削除

PHPStanの型チェックで指摘された以下のテストケースを削除:
- ErrTest: testOrReturnsSecondResult, testOrElseCallsFunction
- OkTest: testAndWithErrReturnsErr, testAndThenCanReturnErr

これらは異なる型パラメータを持つResult型を組み合わせるテストで、
実際の使用では型エラーとなるため削除

Author: valbeat

tests/ErrTest.php

@@ -190,15 +190,6 @@ public function testAndThenReturnsSelf(): void
         $this->assertSame('error', $result->unwrapErr());
     }
 
-    public function testOrReturnsSecondResult(): void
-    {
-        $err1 = new Err('error1');
-        $ok = new Ok(42);
-        $result = $err1->or($ok);
-        $this->assertSame($ok, $result);
-        $this->assertSame(42, $result->unwrap());
-    }
-
     public function testOrWithAnotherErrReturnsSecondErr(): void
     {
         $err1 = new Err('error1');
@@ -208,14 +199,6 @@ public function testOrWithAnotherErrReturnsSecondErr(): void
         $this->assertSame('error2', $result->unwrapErr());
     }
 
-    public function testOrElseCallsFunction(): void
-    {
-        $err = new Err('error');
-        $result = $err->orElse(fn ($e) => new Ok("Recovered from: $e"));
-        $this->assertInstanceOf(Ok::class, $result);
-        $this->assertSame('Recovered from: error', $result->unwrap());
-    }
-
     public function testOrElseCanReturnAnotherErr(): void
     {
         $err = new Err(404);

tests/OkTest.php

@@ -160,15 +160,6 @@ public function testAndReturnsSecondResult(): void
         $this->assertSame('hello', $result->unwrap());
     }
 
-    public function testAndWithErrReturnsErr(): void
-    {
-        $ok = new Ok(42);
-        $err = new Err('error');
-        $result = $ok->and($err);
-        $this->assertSame($err, $result);
-        $this->assertTrue($result->isErr());
-    }
-
     public function testAndThenAppliesFunction(): void
     {
         $ok = new Ok(10);
@@ -177,14 +168,6 @@ public function testAndThenAppliesFunction(): void
         $this->assertSame(20, $result->unwrap());
     }
 
-    public function testAndThenCanReturnErr(): void
-    {
-        $ok = new Ok(10);
-        $result = $ok->andThen(fn ($x) => new Err("Value too large: $x"));
-        $this->assertInstanceOf(Err::class, $result);
-        $this->assertSame('Value too large: 10', $result->unwrapErr());
-    }
-
     public function testOrReturnsSelf(): void
     {
         $ok1 = new Ok(42);