feat: add icon field to application schema with size validation

- Introduced a new optional `icon` field to the application schema, allowing for icon uploads.
- Implemented validation to ensure the icon size does not exceed 2MB, enhancing data integrity.

packages/server/src/db/schema/application.ts

@@ -373,6 +373,7 @@ const createSchema = createInsertSchema(applications, {
 	endpointSpecSwarm: EndpointSpecSwarmSchema.nullable(),
 	ulimitsSwarm: UlimitsSwarmSchema.nullable(),
 	enableSubmodules: z.boolean().optional(),
+	icon: z.string().max(2 * 1024 * 1024, "Icon must be less than 2MB").nullable().optional(),
 });
 
 export const apiCreateApplication = createSchema.pick({