fix: parser newline handling in lists and stdlib exports

- Fix parse_list_expr to skip newlines between list elements
- Add `pub` keyword to all exported functions in stdlib/html.lux
- Change List.foldl to List.fold (matching built-in name)
- Update weaknesses document with fixed issues

The module import system now works correctly. This enables:
- import stdlib/html to work as expected
- html.div(), html.render() etc. to be accessible
- Multi-line list expressions in Lux source files

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/parser.rs

@@ -2266,12 +2266,15 @@ impl Parser {
     fn parse_list_expr(&mut self) -> Result<Expr, ParseError> {
         let start = self.current_span();
         self.expect(TokenKind::LBracket)?;
+        self.skip_newlines();
 
         let mut elements = Vec::new();
         while !self.check(TokenKind::RBracket) {
             elements.push(self.parse_expr()?);
+            self.skip_newlines();
             if !self.check(TokenKind::RBracket) {
                 self.expect(TokenKind::Comma)?;
+                self.skip_newlines();
             }
         }