feat(app): export isDev platform flag and enable runtime metrics in dev

Adds a shared isDev constant alongside isWeb/isNative and wires daemon
clients to collect runtime metrics (10s interval) only in development.

packages/app/src/runtime/host-runtime.ts

@@ -30,6 +30,7 @@ import {
   buildLocalDaemonTransportUrl,
   createDesktopLocalDaemonTransportFactory,
 } from "@/desktop/daemon/desktop-daemon-transport";
+import { isDev } from "@/constants/platform";
 import { applyFetchedAgentDirectory } from "@/utils/agent-directory-sync";
 import { useSessionStore, type Agent } from "@/stores/session-store";
 
@@ -433,6 +434,7 @@ function createDefaultDeps(): HostRuntimeControllerDeps {
         clientType: "mobile" as const,
         appVersion: resolveAppVersion() ?? undefined,
         runtimeGeneration,
+        ...(isDev ? { runtimeMetricsIntervalMs: 10_000 } : {}),
       };
       if (connection.type === "directSocket" || connection.type === "directPipe") {
         return new DaemonClient({