refactor: adapted lexer to work with new tokens

Now its fine, the code i find it clear if one just sits down to read it
for a moment, next is the parser that REALLY needs reworking and a few
helper structs.

include/lexer.h

@@ -61,7 +61,7 @@ typedef struct {
     bool is_valid;
     union {
         LexerErr err;
-        int64_t number;
+        int64_t num;
     };
 } LexerI64Result;