Add shared types package

Shared TypeScript types, Zod validators, API contract definitions,
and constants used by both server and UI. Covers agents, goals,
issues, projects, and activity entities.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/shared/src/validators/project.ts

@@ -0,0 +1,12 @@
+import { z } from "zod";
+
+export const createProjectSchema = z.object({
+  name: z.string().min(1),
+  description: z.string().optional().nullable(),
+});
+
+export type CreateProject = z.infer<typeof createProjectSchema>;
+
+export const updateProjectSchema = createProjectSchema.partial();
+
+export type UpdateProject = z.infer<typeof updateProjectSchema>;