M9: monetisation decision - one-time paid, no billing code, verified in release APK

docs/PLAY_RELEASE_CHECKLIST.md

@@ -122,8 +122,14 @@ factor too).
 
 - [ ] Create the app, complete *App content*, then roll out
       **internal → closed → production**, checking the pre-launch report on the way.
-- [ ] ⚠️ **Set the price before the first upload** (M9). Once an app has been offered for
-      free it can never be made paid, and this app is a **one-time paid** app: no ads, no
-      subscription, no in-app purchases — and therefore no Billing code and no
-      `com.android.vending.BILLING` permission in the APK. The price lives on the listing,
-      not in the build.
+- [ ] ⚠️ **Set the price before the first upload.** Play's own wording: *"You can change your
+      app from paid to free. Once your app has been offered for free, the app can't be
+      changed to paid."* So:
+      1. Create a **payments profile** (identity, tax, bank details).
+      2. *Products › App pricing*: base price **€4.49**.
+      3. Launch price **€2.29** for the first **14 days**, then diarise changing it back.
+      4. Do every step above **before uploading**.
+- [x] **[code] no Billing client and no `BILLING` permission** — the price lives on the
+      listing, not in the build, so the APK contains no purchase code at all. Verified
+      2026-10-14 against the release APK. Full rationale and the rejected alternatives:
+      [MONETISATION](MONETISATION.md).