Add form styles and update button classes for consistency

- Introduced a new CSS file for form styles (forms.css) to enhance form layout and design.
- Removed deprecated button styles from imports.css and updated button classes across templates to use the new utility classes.
- Updated various templates to reflect the new button styles, ensuring a consistent look and feel throughout the application.
- Refactored form-related styles in main.css and removed redundant styles from projects.css and scenarios.css.
- Ensured responsive design adjustments for form actions in smaller viewports.

templates/imports/ui.html

@@ -24,8 +24,8 @@
   {% include "partials/import_preview_table.html" %}
 
       <div class="import-actions hidden" data-import-actions>
-        <button class="btn primary" data-import-commit disabled>Commit Import</button>
-        <button class="btn" data-import-cancel>Cancel</button>
+        <button class="btn btn--primary" data-import-commit disabled>Commit Import</button>
+        <button class="btn btn--secondary" data-import-cancel>Cancel</button>
       </div>
     </div>
   </section>