App 2.19.3: update log on the Logs tab

Every update and install step, with the platform's own result, kept
across the restart an install causes, so a failed install on the car
can be read off the screen.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LhzAVaUyqcw5PkGjz4mWW6

AGENTS.md

@@ -114,7 +114,9 @@ cd server && go vet ./... && go test ./... && govulncheck ./...
   car's platform key, so the car build installs as the system user. `adb shell wm size 1778x640`
   gives the car's app window (taps then use those coordinates; screenshots stay 1920×720). It has
   no car data (every value is "—"). While the app is open, `uiautomator dump` never sees an idle
-  screen; use screenshots.
+  screen; use screenshots. A USB stick: a FAT image (`mkfs.vfat`, files in with `mcopy`) passed as
+  `-sdcard <image>` mounts as a removable volume like the car's stick; `adb push` to
+  `/storage/<id>/` changes it while running.
 - **After each change:** a `SPECS.md` done-log entry, docs that the change affects, explicit
   staging, commit, push.