chore: Use relative pre-imports to avoid KeyError

Author: markusdlugi

src/solarbatteryield/__init__.py

@@ -10,8 +10,9 @@
 # Pre-import modules to ensure they are fully loaded before concurrent access.
 # This prevents race conditions with @dataclass decorators on Streamlit Cloud.
 # Order matters: import dependencies before dependents.
-from solarbatteryield import inverter_efficiency  # noqa: F401  - needed by models, simulation
-from solarbatteryield import h0_profile  # noqa: F401  - needed by config, simulation
-from solarbatteryield import load_regression  # noqa: F401  - JSON loaded at module level
-from solarbatteryield import config  # noqa: F401  - needed by state, sidebar, report
-from solarbatteryield import models  # noqa: F401  - needed by simulation, report
+# Use relative imports to avoid KeyError during package initialization.
+from . import inverter_efficiency  # noqa: F401  - needed by models, simulation
+from . import h0_profile  # noqa: F401  - needed by config, simulation
+from . import load_regression  # noqa: F401  - JSON loaded at module level
+from . import config  # noqa: F401  - needed by state, sidebar, report
+from . import models  # noqa: F401  - needed by simulation, report