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/application_setting.py

@@ -14,15 +14,24 @@ class ApplicationSetting(Base):
     id: Mapped[int] = mapped_column(primary_key=True, index=True)
     key: Mapped[str] = mapped_column(String(128), unique=True, nullable=False)
     value: Mapped[str] = mapped_column(Text, nullable=False)
-    value_type: Mapped[str] = mapped_column(String(32), nullable=False, default="string")
-    category: Mapped[str] = mapped_column(String(32), nullable=False, default="general")
+    value_type: Mapped[str] = mapped_column(
+        String(32), nullable=False, default="string"
+    )
+    category: Mapped[str] = mapped_column(
+        String(32), nullable=False, default="general"
+    )
     description: Mapped[Optional[str]] = mapped_column(Text, nullable=True)
-    is_editable: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True)
+    is_editable: Mapped[bool] = mapped_column(
+        Boolean, nullable=False, default=True
+    )
     created_at: Mapped[datetime] = mapped_column(
         DateTime(timezone=True), server_default=func.now(), nullable=False
     )
     updated_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), server_default=func.now(), onupdate=func.now(), nullable=False
+        DateTime(timezone=True),
+        server_default=func.now(),
+        onupdate=func.now(),
+        nullable=False,
     )
 
     def __repr__(self) -> str: