feat: add IsPalindrome snippet with unit test and README entry

src/main/kotlin/codecollection/snippets/strings/IsPalindrome.kt

@@ -0,0 +1,6 @@
+package codecollection.snippets.strings
+
+fun isPalindrome(input: String): Boolean {
+    val filtered = input.filter { it.isLetterOrDigit() }.lowercase()
+    return filtered == filtered.reversed()
+}

src/main/kotlin/codecollection/snippets/strings/README.md

@@ -12,5 +12,6 @@ Each snippet is implemented as an extension function or utility method, and test
 |--------------------------------------------------|---------------------------------------|
 | [`ConvertToCamelCase.kt`](ConvertToCamelCase.kt) | Converts strings to camelCase format  |
 | [`ReplaceMultipleSpaces.kt`](ReplaceMultipleSpaces.kt) | Replaces consecutive whitespace with a single space  |
+| [`IsPalindrome.kt`](IsPalindrome.kt)              | Checks whether the string is a palindrome or not|
 | _More coming soon..._                            |                                       |
 

src/test/kotlin/codecollection/snippets/strings/IsPalindromeTest.kt

@@ -0,0 +1,23 @@
+package codecollection.snippets.strings
+
+import kotlin.test.Test
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+class IsPalindromeTest {
+
+    @Test
+    fun testPalindromeWithSimpleWord() {
+        assertTrue(isPalindrome("madam"))
+    }
+
+    @Test
+    fun testPalindromeWithPunctuation() {
+        assertTrue(isPalindrome("A man, a plan, a canal: Panama"))
+    }
+
+    @Test
+    fun testNonPalindrome() {
+        assertFalse(isPalindrome("hello"))
+    }
+}