fix: module syntax — changed src_bux/*.bux from module X; to module X { ... }

src_bux/lexer.bux

@@ -1,6 +1,6 @@
 // lexer.bux — Lexer state machine (ported from lexer.nim)
 // Tokenizes Bux source into a stream of tokens.
-module Lexer;
+module Lexer {
 
 extern func bux_strlen(s: String) -> uint;
 
@@ -693,4 +693,4 @@ func Lexer_Free(lex: *Lexer) {
     bux_free(lex.tokens as *void);
     bux_free(lex.diags as *void);
     bux_free(lex as *void);
-}
+}