README: current tabs, updating, emulator; screenshots of all tabs from 2.18.1

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QLJfZQZeAKAwSqViTmLzki

OTA.md

@@ -10,7 +10,7 @@ build-car ─▶ publish-car ─▶ forge pre-release (private repo, git.stinnes
                            car server  /v1/app/releases, /v1/app/assets/…
                                    │  the car's own paired token
                                    ▼
-                    app: refresh button → check → SHA-256 → install
+          app: Settings → Check for updates → SHA-256 → install
 ```
 
 The repository stays private and the forge token stays on the server: the car asks its own
@@ -51,7 +51,7 @@ The version comes from the **asset file name**, not the tag.
 
 ## Installing
 
-Press the refresh button in the app's top bar. The app checks, downloads the APK into
+Press **Check for updates** on the Settings tab. The app checks, downloads the APK into
 **Downloads** (with progress), verifies its SHA-256, and hands it to a `PackageInstaller`
 session. As the system user it may install without asking; if the platform wants a
 confirmation, the confirmation screen opens. When a session cannot start at all, the file