refactor(dns-cache): drop legacy DNS migration paths

Removes the json-blob and SharedPreferences reclaim routines now that
the binary format is the first persisted shape — no users carry the
older blobs.

amethyst/src/main/java/com/vitorpamplona/amethyst/AppModules.kt

@@ -559,9 +559,6 @@ class AppModules(
         // once restored, every previously-seen host hits the stale-while-revalidate path
         // instead of blocking on getaddrinfo.
         applicationIOScope.launch {
-            // One-shot reclaim of the legacy SharedPreferences blob — SurgeDnsStore moved
-            // from storage to cacheDir.
-            appContext.deleteSharedPreferences("amethyst_dns_cache")
             dnsStore.load()
         }
 

amethyst/src/main/java/com/vitorpamplona/amethyst/service/okhttp/SurgeDnsStore.kt

@@ -71,12 +71,6 @@ class SurgeDnsStore(
      * call from a background thread.
      */
     fun load() {
-        // One-shot reclaim of the legacy JSON blob — this class moved to a binary format. Done
-        // here (not in the constructor) so the syscall happens on the load() background thread
-        // instead of whatever thread builds the store.
-        val legacy = File(file.parentFile, LEGACY_FILE_NAME)
-        if (legacy.exists()) legacy.delete()
-
         if (!file.exists()) return
         val records =
             try {
@@ -192,7 +186,6 @@ class SurgeDnsStore(
     companion object {
         private const val TAG = "SurgeDnsStore"
         const val FILE_NAME = "dns_cache_v1.bin"
-        private const val LEGACY_FILE_NAME = "dns_cache_v1.json"
 
         // 'SNSC' — Surge dNS Cache.
         private const val MAGIC = 0x534E5343

amethyst/src/test/java/com/vitorpamplona/amethyst/service/okhttp/SurgeDnsStoreTest.kt

@@ -155,19 +155,4 @@ class SurgeDnsStoreTest {
         store.load() // must not throw
         assertTrue(dns.snapshot().isEmpty())
     }
-
-    @Test
-    fun `load deletes the legacy json sibling`() {
-        val legacy = File(tempFolder.root, "dns_cache_v1.json")
-        legacy.writeText("[]")
-        assertTrue(legacy.exists())
-
-        val target = File(tempFolder.root, "dns_cache_v1.bin")
-        val (store, _) = newStore(target)
-        // Construction must not touch the filesystem — only load() may.
-        assertTrue("constructor should not delete legacy file", legacy.exists())
-
-        store.load()
-        assertFalse("legacy json blob should be reclaimed by load()", legacy.exists())
-    }
 }