chore: add a justfile for common dev commands

justfile

@@ -0,0 +1,23 @@
+# Common development commands for OpenEnv. Run `just` to list recipes.
+
+export PYTHONPATH := "src:envs"
+
+# List available recipes
+default:
+    @just --list
+
+# Install dependencies
+install:
+    uv sync --all-extras
+
+# Run the test suite (excludes envs that need special setup, like CI)
+test:
+    uv run pytest tests/ -v --tb=short \
+        --ignore=tests/envs/test_browsergym_environment.py \
+        --ignore=tests/envs/test_dipg_environment.py \
+        --ignore=tests/envs/test_websearch_environment.py \
+        -m "not integration and not network and not docker"
+
+# Run a single test file or pattern, e.g. `just test-one tests/core/test_agentic_harness_types.py`
+test-one target:
+    uv run pytest {{target}} -v --tb=short