Runtime: add method dispatch for array/string/dict/number (.len, .push, .pop, .keys, .values, .has, .toInt)
Stdlib: delete global len/push/pop/keys/values/has
Tests/docs/examples: migrate to method style; add tests/test_builtin_methods_style.bob
All tests pass
Breaking: global len/push/pop/keys/values/has removed; use methods instead
Parser/AST: add class/extends/extension/super, field initializers
Runtime: shared methods with this injection; classParents/classTemplates; super resolution; ownerClass/currentClass; extension lookup order
Builtins: method dispatch for array/string/dict/number (.len/.push/.pop/.keys/.values/.has/.toInt); remove global forms
Tests/docs/examples: add/refresh for classes, inheritance, super, polymorphism; migrate to method style; all tests pass
VS Code extension: update grammar/readme/snippets for new features
