feat: make responsiblePerson required on project creation/edit

- Zod schema: responsiblePerson now min(1) required, no longer optional
- ProjectModal: required indicator (*), HTML required attribute, no undefined fallback
- ProjectWizard: same fix for create flow
- Existing projects with null responsiblePerson still work (DB allows null)
- Validation enforced at API boundary on new creates/updates

Co-Authored-By: claude-flow <ruv@ruv.net>

packages/shared/src/schemas/project.schema.ts

@@ -28,7 +28,7 @@ export const CreateProjectBaseSchema = z.object({
   dynamicFields: z.record(z.string(), z.unknown()).default({}),
   blueprintId: z.string().optional(),
   status: z.nativeEnum(ProjectStatus).default(ProjectStatus.DRAFT),
-  responsiblePerson: z.string().max(200).optional(),
+  responsiblePerson: z.string().min(1, "Responsible person is required").max(200),
   color: z.string().regex(/^#[0-9a-fA-F]{6}$/, "Must be a hex color like #3b82f6").optional(),
   utilizationCategoryId: z.string().optional(),
   clientId: z.string().optional(),