Route application diagnostics through owned log paths

src/apps/webapp/WebAppLog.ts

@@ -0,0 +1,4 @@
+import type { LOG_LEVEL } from "@vrtmrz/livesync-commonlib/compat/common/types";
+
+/** Diagnostic output supplied by the Webapp host. */
+export type WebAppLog = (message: unknown, level: LOG_LEVEL, key?: string) => void;