ci(android): publish tagged releases to the closed testing track

Internal testing is a separate track and does not count toward the
12-tester, 14-day requirement for production access -- only a closed
test does. Releases were landing on internal, so reaching the testers
meant promoting each build by hand in the Console.

Point tracks: at alpha, the closed track, and update the publishing
guide and android README to match. An unknown track id fails the step
with the list of valid tracks rather than publishing somewhere
unintended, so the id is checked at upload time.

Builds up to v0.1.1 remain on the internal track.

.github/workflows/android-release.yml

@@ -66,8 +66,11 @@ jobs:
       # Auto-publish to Google Play (gated on the service-account secret).
       # Skips silently if PLAY_SERVICE_ACCOUNT_JSON is not configured, so
       # tagging a release before Play setup still produces a GH Release.
-      # Default track is "internal" — change to alpha/beta/production
-      # once you trust the pipeline.
+      # Uploads to "alpha", the closed-testing track. Internal testing is a
+      # separate track and does not count toward the 12-tester requirement
+      # for production access, so releases have to land here to reach the
+      # testers. An unknown track name fails the step with the list of
+      # valid tracks rather than publishing somewhere unintended.
       - name: Check Play Store config
         id: play
         env:
@@ -80,14 +83,14 @@ jobs:
             echo "::notice::PLAY_SERVICE_ACCOUNT_JSON not set; skipping Play Store upload."
           fi
 
-      - name: Upload to Google Play (internal track)
+      - name: Upload to Google Play (closed testing track)
         if: steps.play.outputs.configured == 'true'
         uses: r0adkll/upload-google-play@e738b9dd8f2476ea806d921b64aacd24f34515a5 # v1.1.5
         with:
           serviceAccountJsonPlainText: ${{ secrets.PLAY_SERVICE_ACCOUNT_JSON }}
           packageName: com.miti99.loto
           releaseFiles: android/android/app/build/outputs/bundle/release/*.aab
-          tracks: internal
+          tracks: alpha
           status: completed
           # Bumps versionCode automatically? No — must be incremented
           # manually in android/android/app/build.gradle before tagging.