feat: implement app-side telemetry sender

Add the shared telemetry sender, wire the CLI/server emit points,
and cover the config and completion behavior with tests.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

cli/src/__tests__/allowed-hostname.test.ts

@@ -44,6 +44,9 @@ function writeBaseConfig(configPath: string) {
       baseUrlMode: "auto",
       disableSignUp: false,
     },
+    telemetry: {
+      enabled: true,
+    },
     storage: {
       provider: "local_disk",
       localDisk: { baseDir: "/tmp/paperclip-storage" },