feat(classic): add progress callback to ClassicCardReader for key recovery status

Thread an onProgress callback through ClassicCardReader.readCard so the
UI can report nested attack key recovery status. The desktop PN53x backend
prints progress messages to the console. The parameter defaults to null
so existing callers are unaffected.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Claude

app/desktop/src/jvmMain/kotlin/com/codebutler/farebot/desktop/PN53xReaderBackend.kt

@@ -163,7 +163,9 @@ abstract class PN53xReaderBackend(
 
             CardType.MifareClassic -> {
                 val tech = PN533ClassicTechnology(pn533, target.tg, tagId, info)
-                ClassicCardReader.readCard(tagId, tech, null)
+                ClassicCardReader.readCard(tagId, tech, null) { progress ->
+                    println("[$name] $progress")
+                }
             }
 
             CardType.MifareUltralight -> {

card/classic/src/commonMain/kotlin/com/codebutler/farebot/card/classic/ClassicCardReader.kt

@@ -52,6 +52,7 @@ object ClassicCardReader {
         tech: ClassicTechnology,
         cardKeys: ClassicCardKeys?,
         globalKeys: List<ByteArray>? = null,
+        onProgress: ((String) -> Unit)? = null,
     ): RawClassicCard {
         val sectors = ArrayList<RawClassicSector>()
         val recoveredKeys = mutableMapOf<Int, Pair<ByteArray, Boolean>>()
@@ -173,12 +174,15 @@ object ClassicCardReader {
                         val rawClassic = PN533RawClassic(tech.rawPn533, tech.rawUid)
                         val attack = NestedAttack(rawClassic, tech.uidAsUInt)
 
+                        onProgress?.invoke("Sector $sectorIndex: attempting key recovery...")
+
                         val recoveredKey = attack.recoverKey(
                             knownKeyType = knownKeyType,
                             knownSectorBlock = knownBlock,
                             knownKey = knownKey,
                             targetKeyType = 0x60,
                             targetBlock = targetBlock,
+                            onProgress = onProgress,
                         )
 
                         if (recoveredKey != null) {
@@ -195,6 +199,9 @@ object ClassicCardReader {
                                     isKeyA = false
                                 }
                             }
+                            if (authSuccess) {
+                                onProgress?.invoke("Sector $sectorIndex: key recovered!")
+                            }
                         }
                     }
                 }