🐛 Fix: Remove JVM-only @volatile annotation from commonMain

@volatile is also JVM-specific and not available in Kotlin common code.

Author: Raoof128

common/src/commonMain/kotlin/com/qrshield/security/RateLimiter.kt

@@ -270,7 +270,8 @@ class Throttler(
     private val clock: () -> Long = { Clock.System.now().toEpochMilliseconds() }
 ) {
 
-    @Volatile
+    // Note: For thread-safe access, use the suspend variants with Mutex
+    // The non-suspend methods are for single-threaded UI access
     private var lastOperationTime: Long = 0L
 
     private val mutex = Mutex()