feat(core): add GuardScanner interface and ScanResult data class #47

This commit introduces a new GuardScanner interface and a corresponding ScanResult data class to the core module. The GuardScanner interface defines a method for scanning input, while the ScanResult class encapsulates the result of a scan operation.

core/src/main/kotlin/com/phodal/shirecore/guard/GuardScanner.kt

@@ -0,0 +1,13 @@
+package com.phodal.shirecore.guard
+
+// Define a common interface for all scanners
+interface GuardScanner {
+    fun scan(input: String): ScanResult
+}
+
+// Define a ScanResult class to encapsulate the result of a scan
+data class ScanResult(
+    val isPassed: Boolean,
+    val modifiedInput: String? = null,
+    val message: String? = null
+)