Add server routes for companies, approvals, costs, and dashboard

New routes: companies, approvals, costs, dashboard, authz. New
services: companies, approvals, costs, dashboard, heartbeat,
activity-log. Add auth middleware and structured error handling.
Expand existing agent and issue routes with richer CRUD operations.

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

server/src/types/express.d.ts

@@ -0,0 +1,15 @@
+export {};
+
+declare global {
+  namespace Express {
+    interface Request {
+      actor: {
+        type: "board" | "agent";
+        userId?: string;
+        agentId?: string;
+        companyId?: string;
+        keyId?: string;
+      };
+    }
+  }
+}