Refactor test cases for improved readability and consistency

- Updated test functions in various test files to enhance code clarity by formatting long lines and improving indentation.
- Adjusted assertions to use multi-line formatting for better readability.
- Added new test cases for theme settings API to ensure proper functionality.
- Ensured consistent use of line breaks and spacing across test files for uniformity.

models/parameters.py

@@ -10,14 +10,17 @@ class Parameter(Base):
 
     id: Mapped[int] = mapped_column(primary_key=True, index=True)
     scenario_id: Mapped[int] = mapped_column(
-        ForeignKey("scenario.id"), nullable=False)
+        ForeignKey("scenario.id"), nullable=False
+    )
     name: Mapped[str] = mapped_column(nullable=False)
     value: Mapped[float] = mapped_column(nullable=False)
     distribution_id: Mapped[Optional[int]] = mapped_column(
-        ForeignKey("distribution.id"), nullable=True)
+        ForeignKey("distribution.id"), nullable=True
+    )
     distribution_type: Mapped[Optional[str]] = mapped_column(nullable=True)
     distribution_parameters: Mapped[Optional[Dict[str, Any]]] = mapped_column(
-        JSON, nullable=True)
+        JSON, nullable=True
+    )
 
     scenario = relationship("Scenario", back_populates="parameters")
     distribution = relationship("Distribution")