fix: 输入校验忽略多个连续空格与大小写；统一中英文引号与空白规范化

kouyu_english/test/writing_feedback_test.dart

@@ -31,4 +31,31 @@ void main() {
       isTrue,
     );
   });
+
+  test('ignores multiple spaces, mixed casing and curly apostrophes', () {
+    // a0-01 greeting and name with multiple spaces and uppercase
+    expect(
+      WritingFeedback.check('a0-01', '   HELLO   I   AM   ALEX   ').complete,
+      isTrue,
+    );
+    // a0-01 with curly quote and multiple spaces
+    expect(
+      WritingFeedback.check('a0-01', 'HI    I’M   MIA').complete,
+      isTrue,
+    );
+    // a0-07 with multiple spaces in phrase
+    expect(
+      WritingFeedback.check('a0-07', 'THIS    IS    MY    MOTHER').complete,
+      isTrue,
+    );
+    // a0-08-c with multiple spaces and curly apostrophe
+    expect(
+      WritingFeedback.check(
+        'a0-08-c',
+        'IT’S    THREE    O’CLOCK',
+        segmentId: 'a0-08-c',
+      ).complete,
+      isTrue,
+    );
+  });
 }