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/lib/api/types/Company.ts

@@ -35,9 +35,9 @@ export interface ICreateCompanyCredentials {
   website: string;
   type: string;
   description: string;
-  founded_year: number;
-  employee_count: number;
-  annual_revenue: number;
+  founded_year?: number | string;
+  employee_count?: number | string;
+  annual_revenue?: number | string;
   currency: string;
   industry: string;
   language: string;

src/lib/api/types/TCompany.ts

@@ -35,9 +35,9 @@ export interface ICreateCompanyCredentials {
   website: string;
   type: string;
   description: string;
-  founded_year: number;
-  employee_count: number;
-  annual_revenue: number;
+  founded_year?: number | string;
+  employee_count?: number | string;
+  annual_revenue?: number | string;
   currency: string;
   industry: string;
   language: string;