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/agent.ts

@@ -0,0 +1,20 @@
+import { z } from "zod";
+import { AGENT_ROLES, AGENT_STATUSES } from "../constants.js";
+
+export const createAgentSchema = z.object({
+  name: z.string().min(1),
+  role: z.enum(AGENT_ROLES),
+  budgetCents: z.number().int().nonnegative().optional().default(0),
+  reportsTo: z.string().uuid().optional().nullable(),
+  metadata: z.record(z.unknown()).optional().nullable(),
+});
+
+export type CreateAgent = z.infer<typeof createAgentSchema>;
+
+export const updateAgentSchema = createAgentSchema
+  .partial()
+  .extend({
+    status: z.enum(AGENT_STATUSES).optional(),
+  });
+
+export type UpdateAgent = z.infer<typeof updateAgentSchema>;