feat: implement logical AND operator with short-circuit evaluation and new CODE_AND instruction

Add TOKEN_AMPAMP token to the lexer for parsing '&&' operator, introduce PREC_LOGIC precedence level for proper expression parsing, implement the `and()` compiler function that emits CODE_AND with a patchable jump offset, and add runtime support in the VM with IS_FALSE macro for truthiness checking. Include comprehensive test cases in test/and.wren verifying short-circuit behavior and return values.

test/and.wren

@@ -0,0 +1,20 @@
+// Note: These tests implicitly depend on ints being truthy.
+//       Also rely on io.write() returning its argument.
+
+// Return the first non-true argument.
+io.write(false && 1) // expect: false
+io.write(true && 1) // expect: 1
+io.write(1 && 2 && false) // expect: false
+
+// Return the last argument if all are true.
+io.write(1 && true) // expect: true
+io.write(1 && 2 && 3) // expect: 3
+
+// Short-circuit at the first false argument.
+io.write(true) && // expect: true
+    io.write(false) && // expect: false
+    io.write(false) // should not print
+
+// Swallow a trailing newline.
+io.write(true &&
+    true) // expect: true