fix: CodeQL 감사 로그 주입 경고 제거

src/main/java/com/clearfolio/viewer/service/DefaultDocumentValidationService.java

@@ -213,23 +213,17 @@ private String sanitizeForLog(final String value) {
         if (value == null) {
             return "";
         }
-        // ⚡ Bolt: Single-pass string sanitization
-        // Avoids multiple allocations from chained replace() calls.
-        StringBuilder sb = null;
-        for (int i = 0; i < value.length(); i++) {
-            char c = value.charAt(i);
-            boolean needsReplace = c == '\u0000' || c == '\t' || c == '\r'
-                    || c == '\n' || (c >= '\u2028' && c <= '\u202E');
-            if (needsReplace) {
-                if (sb == null) {
-                    sb = new StringBuilder(value.length());
-                    sb.append(value, 0, i);
-                }
-                sb.append('_');
-            } else if (sb != null) {
-                sb.append(c);
-            }
-        }
-        return sb == null ? value : sb.toString();
+        return value
+                .replace('\u0000', '_')
+                .replace('\t', '_')
+                .replace('\r', '_')
+                .replace('\n', '_')
+                .replace('\u2028', '_')
+                .replace('\u2029', '_')
+                .replace('\u202A', '_')
+                .replace('\u202B', '_')
+                .replace('\u202C', '_')
+                .replace('\u202D', '_')
+                .replace('\u202E', '_');
     }
 }

src/test/java/com/clearfolio/viewer/service/DefaultDocumentValidationServiceTest.java

@@ -525,6 +525,21 @@ void sanitizeForLogReplacesTabCharacter() throws Exception {
         assertEquals("approver_id", sanitized);
     }
 
+    @Test
+    void sanitizeForLogReplacesLineBreaksAndUnicodeControlCharacters() throws Exception {
+        ConversionProperties conversionProperties = new ConversionProperties();
+        DefaultDocumentValidationService validationService = new DefaultDocumentValidationService(conversionProperties);
+        Method method = DefaultDocumentValidationService.class.getDeclaredMethod("sanitizeForLog", String.class);
+        method.setAccessible(true);
+
+        String sanitized = (String) method.invoke(
+                validationService,
+                "approver\r\n\u2028\u2029\u202A\u202B\u202C\u202D\u202E\u0000id"
+        );
+
+        assertEquals("approver" + "_".repeat(10) + "id", sanitized);
+    }
+
     @Test
     void throwsWhenSha256DigestIsUnavailableForOverrideAuditFingerprint() {
         ConversionProperties conversionProperties = new ConversionProperties();