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.

tests/e2e/test_smoke.py

@@ -5,7 +5,11 @@ from playwright.sync_api import Page, expect
 UI_ROUTES = [
     ("/", "Dashboard · CalMiner", "Operations Overview"),
     ("/ui/dashboard", "Dashboard · CalMiner", "Operations Overview"),
-    ("/ui/scenarios", "Scenario Management · CalMiner", "Create a New Scenario"),
+    (
+        "/ui/scenarios",
+        "Scenario Management · CalMiner",
+        "Create a New Scenario",
+    ),
     ("/ui/parameters", "Process Parameters · CalMiner", "Scenario Parameters"),
     ("/ui/settings", "Settings · CalMiner", "Settings"),
     ("/ui/costs", "Costs · CalMiner", "Cost Overview"),
@@ -20,35 +24,44 @@ UI_ROUTES = [
 
 
 @pytest.mark.parametrize("url, title, heading", UI_ROUTES)
-def test_ui_pages_load_correctly(page: Page, url: str, title: str, heading: str):
+def test_ui_pages_load_correctly(
+    page: Page, url: str, title: str, heading: str
+):
     """Verify that all UI pages load with the correct title and a visible heading."""
     page.goto(url)
     expect(page).to_have_title(title)
     # The app uses a mix of h1 and h2 for main page headings.
     heading_locator = page.locator(
-        f"h1:has-text('{heading}'), h2:has-text('{heading}')")
+        f"h1:has-text('{heading}'), h2:has-text('{heading}')"
+    )
     expect(heading_locator.first).to_be_visible()
 
 
 def test_settings_theme_form_interaction(page: Page):
-    page.goto("/ui/settings")
-    expect(page).to_have_title("Settings · CalMiner")
+    page.goto("/theme-settings")
+    expect(page).to_have_title("Theme Settings · CalMiner")
 
     env_rows = page.locator("#theme-env-overrides tbody tr")
     disabled_inputs = page.locator(
-        "#theme-settings-form input.color-value-input[disabled]")
+        "#theme-settings-form input.color-value-input[disabled]"
+    )
     env_row_count = env_rows.count()
     disabled_count = disabled_inputs.count()
     assert disabled_count == env_row_count
 
     color_input = page.locator(
-        "#theme-settings-form input[name='--color-primary']")
+        "#theme-settings-form input[name='--color-primary']"
+    )
     expect(color_input).to_be_visible()
     expect(color_input).to_be_enabled()
 
     original_value = color_input.input_value()
     candidate_values = ("#114455", "#225566")
-    new_value = candidate_values[0] if original_value != candidate_values[0] else candidate_values[1]
+    new_value = (
+        candidate_values[0]
+        if original_value != candidate_values[0]
+        else candidate_values[1]
+    )
 
     color_input.fill(new_value)
     page.click("#theme-settings-form button[type='submit']")