feat: validate ADDRESS_CITY against a real city dictionary

The rule matched any capitalized word after "г."/"город" — no check
that it's an actual place. ToponymDictionary checks the match against
1111 Russian cities (pensnarik/russian-cities) plus CIS capitals,
matching by stem so declined forms work ("Москве" against "Москва").

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/test/java/ru/pdguard/detect/ToponymDictionaryTest.java

@@ -0,0 +1,42 @@
+package ru.pdguard.detect;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/** Словарь городов — проверка вместо любого слова с заглавной буквы после «г.». */
+class ToponymDictionaryTest {
+
+    @Test
+    void recognisesNominativeCase() {
+        assertTrue(ToponymDictionary.isKnownCity("Москва"));
+        assertTrue(ToponymDictionary.isKnownCity("Казань"));
+        assertTrue(ToponymDictionary.isKnownCity("Санкт-Петербург"));
+    }
+
+    @Test
+    void recognisesInflectedForms() {
+        assertTrue(ToponymDictionary.isKnownCity("Москве"), "дательный падеж города на гласную");
+        assertTrue(ToponymDictionary.isKnownCity("Тамбове"), "предложный падеж города на согласную");
+        assertTrue(ToponymDictionary.isKnownCity("Казани"), "родительный падеж");
+    }
+
+    @Test
+    void recognisesCisCapitals() {
+        assertTrue(ToponymDictionary.isKnownCity("Минск"));
+        assertTrue(ToponymDictionary.isKnownCity("Алматы"));
+    }
+
+    @Test
+    void rejectsMadeUpWord() {
+        assertFalse(ToponymDictionary.isKnownCity("Ерунда"));
+        assertFalse(ToponymDictionary.isKnownCity("Бла-бла"));
+    }
+
+    @Test
+    void isCaseInsensitive() {
+        assertTrue(ToponymDictionary.isKnownCity("МОСКВА"));
+        assertTrue(ToponymDictionary.isKnownCity("москва"));
+    }
+}