test(conftest): make jax import lazy so tests collect without JAX

JAX is now an optional dep gated on python_version >= '3.11'. The
eager `import jax` at the top of test_autoarray/conftest.py was
breaking pytest collection on 3.9 and 3.10 (no JAX installed).
Wrap in try/except, gate jnp warmup on _JAX_AVAILABLE.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: 2 people

test_autoarray/conftest.py

@@ -1,11 +1,16 @@
-import jax
-import jax.numpy as jnp
+try:
+    import jax
+    import jax.numpy as jnp
 
-jax.config.update("jax_enable_x64", True)
+    jax.config.update("jax_enable_x64", True)
+    _JAX_AVAILABLE = True
+except ImportError:
+    _JAX_AVAILABLE = False
 
 
 def pytest_configure():
-    _ = jnp.sum(jnp.array([0.0]))  # Force backend init
+    if _JAX_AVAILABLE:
+        _ = jnp.sum(jnp.array([0.0]))  # Force backend init
 
 
 import os