feat: add pet-hatch locator for Hatch environments (Fixes #450)

Adds a new pet-hatch crate that detects Hatch-managed virtual environments so they are no longer misclassified as plain Venv by downstream consumers.

Implementation matches Hatch's actual storage layout from src/hatch/env/virtual.py:

- Default storage: <data_dir>/env/virtual/<project_name>/<project_id>/<venv_name> (3 levels deep)

- HATCH_DATA_DIR env var honoured; never silently falls back to platform default when set

\ example from the issue)

- Locator inserted before Venv so Hatch claims its envs first

- 15 unit tests covering layout depth (rejects 2 / 4 levels), HATCH_DATA_DIR semantics, project-local config, and platform defaults

Author: karthiknadig

Cargo.lock

@@ -43,6 +43,7 @@ pub struct Configuration {
 #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord)]
 pub enum LocatorKind {
     Conda,
+    Hatch,
     Homebrew,
     LinuxGlobal,
     MacCommandLineTools,

crates/pet-core/src/lib.rs

@@ -19,6 +19,7 @@ pub enum PythonEnvironmentKind {
     PyenvVirtualEnv, // Pyenv virtualenvs.
     Pipenv,
     Poetry,
+    Hatch,
     MacPythonOrg,
     MacCommandLineTools,
     LinuxGlobal,

crates/pet-core/src/python_environment.rs

@@ -0,0 +1,16 @@
+[package]
+name = "pet-hatch"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+
+[dependencies]
+pet-core = { path = "../pet-core" }
+pet-fs = { path = "../pet-fs" }
+pet-python-utils = { path = "../pet-python-utils" }
+serde = { version = "1.0.226", features = ["derive"] }
+toml = "0.9.7"
+log = "0.4.21"
+
+[dev-dependencies]
+tempfile = "3.13"