perf: remove remaining redundant .resolve() calls on pre-resolved paths

Drop .resolve() from ImportResolver, TestsCache, init_javascript,
create_pr, and filter_functions where callers already pass resolved
paths via CLI init or TestConfig.__post_init__. Also exclude test
and fixture dirs from mypy to match ruff/ty config.

pyproject.toml

@@ -207,6 +207,8 @@ warn_unreachable = true
 install_types = true
 plugins = ["pydantic.mypy"]
 
+exclude = ["tests/", "code_to_optimize/", "pie_test_set/", "experiments/"]
+
 [[tool.mypy.overrides]]
 module = ["jedi", "jedi.api.classes", "inquirer", "inquirer.themes", "numba"]
 ignore_missing_imports = true