feat(accident): update accident field type and enhance textarea styling

- Changed the accident field type from STRING to TEXT in the Accident model to accommodate larger input.
- Increased the minimum height of the textarea in AccidentFormDialog and added font styling for improved readability.

backend/migrations/20260107_change_accident_to_text.sql

@@ -0,0 +1,3 @@
+-- Change accident field from VARCHAR to TEXT to allow longer descriptions
+ALTER TABLE `accident`
+  MODIFY COLUMN `accident` TEXT NOT NULL;