fix(companies): align optional numeric fields with API validation

Make employee_count, annual_revenue, and founded_year truly optional in
the create company form and payload. Add field validation docs and
Cypress e2e coverage for dashboard and notifications.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/components/forms/companies/useCreateCompanyPresenter.ts

@@ -46,12 +46,19 @@ const useCreateCompanyPresenter = ({ defaultValues, editMode, id }: IProps) => {
   const { mutate: updateCompany, isPending: isUpdating } = useUpdateCompany(
     id as string,
   );
+
+  const optionalNumber = (value: unknown) => {
+    if (value === "" || value === null || value === undefined) return undefined;
+
+    return Number(value);
+  };
+
   const onSubmit: SubmitHandler<ICreateCompanyCredentials> = (data) => {
     const formattedData = {
       ...data,
-      founded_year: data.founded_year ? +data.founded_year : 0,
-      employee_count: data.employee_count ? +data.employee_count : 0,
-      annual_revenue: data.annual_revenue ? +data.annual_revenue : 0,
+      founded_year: optionalNumber(data.founded_year),
+      employee_count: optionalNumber(data.employee_count),
+      annual_revenue: optionalNumber(data.annual_revenue),
       document_file_ids: data.document_file_ids ?? [],
       tags: {
         keywords: data?.tags?.keywords?.length ? data?.tags?.keywords : [],