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/config.ts

@@ -0,0 +1,16 @@
+export interface Config {
+  port: number;
+  databaseUrl: string;
+  serveUi: boolean;
+}
+
+export function loadConfig(): Config {
+  const databaseUrl = process.env.DATABASE_URL;
+  if (!databaseUrl) throw new Error("DATABASE_URL is required");
+
+  return {
+    port: Number(process.env.PORT) || 3100,
+    databaseUrl,
+    serveUi: process.env.SERVE_UI === "true",
+  };
+}