feat: execute short-circuit boolean expressions

source/lexer/scan.hon

@@ -28,6 +28,8 @@ keywords strmap.StaticStringMap(TokenKind) :: strmap.init([
     { "while", .while },
     { "true", .true },
     { "false", .false },
+    { "and", .and },
+    { "or", .or },
 ])
 
 #! owns token storage and retains its allocator; release with deinit.
@@ -225,6 +227,7 @@ scan proc(
 
         kind ?TokenKind :: match char {
             '=': .equal
+            '!': .bang
             '<': .less
             '>': .greater
             ',': .comma