feat: implement mass balance validation for Story 7.1

- Added port_mass_flows to Component trait and implements for core components.
- Added System::check_mass_balance and integrated it into the solver.
- Restored connect methods for ExpansionValve, Compressor, and Pipe to fix integration tests.
- Updated Python and C bindings for validation errors.
- Updated sprint status and story documentation.

bindings/python/pyproject.toml

@@ -16,6 +16,11 @@ classifiers = [
     "Topic :: Scientific/Engineering :: Physics",
 ]
 description = "High-performance thermodynamic cycle simulation library"
+dependencies = [
+    "ipykernel>=6.31.0",
+    "maturin>=1.12.4",
+    "numpy>=2.0.2",
+]
 
 [tool.maturin]
 features = ["pyo3/extension-module"]