feat: add lazy skip and take methods to Sequence with SkipSequence and TakeSequence classes

Implement `skip(count)` and `take(count)` on the Sequence class, backed by new SkipSequence and TakeSequence wrapper classes that lazily skip or limit iteration. Includes documentation in the sequence module markdown, core source definitions, and unit tests for edge cases (zero, negative, and overflow counts).

test/core/sequence/skip.wren

@@ -0,0 +1,28 @@
+class TestSequence is Sequence {
+  construct new() {}
+
+  iterate(iterator) {
+    if (iterator == null) return 1
+    if (iterator == 3) return false
+    return iterator + 1
+  }
+
+  iteratorValue(iterator) { iterator }
+}
+
+var test = TestSequence.new().skip(0)
+
+System.print(test is Sequence) // expect: true
+System.print(test) // expect: instance of SkipSequence
+
+// Skipping 0 changes nothing
+System.print(test.toList) // expect: [1, 2, 3]
+
+// Skipping 1 works
+System.print(test.skip(1).toList) // expect: [2, 3]
+
+// Skipping more than length of sequence produces empty list
+System.print(test.skip(4).isEmpty) // expect: true
+
+// Skipping less than 0 changes nothing
+System.print(test.skip(-10).toList) // expect: [1, 2, 3]

test/core/sequence/take.wren

@@ -0,0 +1,28 @@
+class TestSequence is Sequence {
+  construct new() {}
+
+  iterate(iterator) {
+    if (iterator == null) return 1
+    if (iterator == 3) return false
+    return iterator + 1
+  }
+
+  iteratorValue(iterator) { iterator }
+}
+
+var test = TestSequence.new().take(3)
+
+System.print(test is Sequence) // expect: true
+System.print(test) // expect: instance of TakeSequence
+
+// Taking 0 produces empty list
+System.print(test.take(0).isEmpty) // expect: true
+
+// Taking 1 works
+System.print(test.take(1).toList) // expect: [1]
+
+// Taking more than length of sequence produces whole sequence
+System.print(test.take(4).toList) // expect: [1, 2, 3]
+
+// Taking less than 0 produces empty list
+System.print(test.take(-10).isEmpty) // expect: true