This pull request introduces a new utility function for resolving Python virtual environments in a project directory, supporting both the traditional .venv directory and the PEP 832 convention where .venv is a file pointing to the environment. The function is thoroughly tested and integrated into multiple places in the codebase, replacing previous direct .venv path usage to improve compatibility and correctness.

New .venv resolution utility:

• Added resolve_dot_venv to crates/pet-fs/src/path.rs, which resolves .venv as either a directory or a file (per PEP 832), handling absolute and relative paths and validating existence.
• Comprehensive unit tests for resolve_dot_venv covering all edge cases, including missing .venv, directory, file with absolute/relative paths, non-existent targets, whitespace handling, and file-vs-directory distinction.

Integration into environment discovery:

• Updated crates/pet-poetry/src/environment_locations.rs to use resolve_dot_env (likely a wrapper or alias for resolve_dot_venv) instead of directly joining .venv, ensuring correct environment resolution in Poetry projects.
• Updated crates/pet-uv/src/lib.rs to use resolve_dot_env for both workspace root and directory environment detection, ensuring .venv file conventions are supported. [1] [2]
• Updated crates/pet/src/find.rs to use resolve_dot_env when searching for environments in workspace folders, improving detection accuracy.