Add API server with routes, services, and middleware

Express server with CRUD routes for agents, goals, issues, projects,
and activity log. Includes validation middleware, structured error
handling, request logging, and health check endpoint with tests.

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

server/src/routes/activity.ts

@@ -0,0 +1,35 @@
+import { Router } from "express";
+import { z } from "zod";
+import type { Db } from "@paperclip/db";
+import { validate } from "../middleware/validate.js";
+import { activityService } from "../services/activity.js";
+
+const createActivitySchema = z.object({
+  action: z.string().min(1),
+  entityType: z.string().min(1),
+  entityId: z.string().uuid(),
+  agentId: z.string().uuid().optional().nullable(),
+  details: z.record(z.unknown()).optional().nullable(),
+});
+
+export function activityRoutes(db: Db) {
+  const router = Router();
+  const svc = activityService(db);
+
+  router.get("/", async (req, res) => {
+    const filters = {
+      agentId: req.query.agentId as string | undefined,
+      entityType: req.query.entityType as string | undefined,
+      entityId: req.query.entityId as string | undefined,
+    };
+    const result = await svc.list(filters);
+    res.json(result);
+  });
+
+  router.post("/", validate(createActivitySchema), async (req, res) => {
+    const event = await svc.create(req.body);
+    res.status(201).json(event);
+  });
+
+  return router;
+}