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/app.ts

@@ -0,0 +1,42 @@
+import express, { Router } from "express";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+import type { Db } from "@paperclip/db";
+import { httpLogger, errorHandler } from "./middleware/index.js";
+import { healthRoutes } from "./routes/health.js";
+import { agentRoutes } from "./routes/agents.js";
+import { projectRoutes } from "./routes/projects.js";
+import { issueRoutes } from "./routes/issues.js";
+import { goalRoutes } from "./routes/goals.js";
+import { activityRoutes } from "./routes/activity.js";
+
+export function createApp(db: Db, opts: { serveUi: boolean }) {
+  const app = express();
+
+  app.use(express.json());
+  app.use(httpLogger);
+
+  // Mount API routes
+  const api = Router();
+  api.use("/health", healthRoutes());
+  api.use("/agents", agentRoutes(db));
+  api.use("/projects", projectRoutes(db));
+  api.use("/issues", issueRoutes(db));
+  api.use("/goals", goalRoutes(db));
+  api.use("/activity", activityRoutes(db));
+  app.use("/api", api);
+
+  // SPA fallback for serving the UI build
+  if (opts.serveUi) {
+    const __dirname = path.dirname(fileURLToPath(import.meta.url));
+    const uiDist = path.resolve(__dirname, "../../ui/dist");
+    app.use(express.static(uiDist));
+    app.get("*", (_req, res) => {
+      res.sendFile(path.join(uiDist, "index.html"));
+    });
+  }
+
+  app.use(errorHandler);
+
+  return app;
+}