Move to the 1.1 series, from one place rather than three

The series a build is named for was written out three times — in the
build file and in both workflows' tag lines — so bumping it meant
changing all three and a release could be tagged one thing and built as
another. It now lives in gradle.properties as plgVersionSeries, which
the build reads when it stamps the APK and both workflows read when they
name the tag.

Set to 1.1.

versionCode is deliberately left as the CI run number alone, which is
what makes the bump safe: the run number keeps climbing across a change
of series, so 1.1 never looks like a downgrade to Android and an OTA
update is not interrupted. The series is a name for people; the run
number is what the machines compare. The updater already read only the
trailing number, and its comments now say so rather than naming 1.0.

Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_019Pr6B8xDDtJJcb6WJMw7Ud

app/build.gradle.kts

@@ -16,6 +16,11 @@ val buildChannel = System.getenv("PLG_CHANNEL").orEmpty()
 val runNumber = (System.getenv("GITHUB_RUN_NUMBER") ?: "").toIntOrNull() ?: 0
 val stampVersion = buildChannel.isNotEmpty() && runNumber > 0
 
+// The version series, from gradle.properties. Both workflows read the same
+// property when they name a release tag, so the tag and the APK inside it
+// cannot disagree about which series they belong to.
+val versionSeries = (project.findProperty("plgVersionSeries") as String?) ?: "1.0"
+
 // Anything that is not an explicit production build is a dev build: ci.yml
 // stamps "dev", and a local build with nothing set counts as dev too.
 //
@@ -43,12 +48,15 @@ android {
         // know its own channel, so it must survive into the shipped APK. It
         // tracks isDevBuild rather than the stamp alone, so an unstamped local
         // build cannot end up claiming a channel its applicationId contradicts.
+        // versionCode stays the run number and nothing else, so it keeps
+        // climbing across a change of series: bumping 1.0 to 1.1 must not make
+        // an update look like a downgrade to Android.
         versionCode = if (stampVersion) runNumber else 1
         versionName = when {
-            stampVersion && buildChannel == "production" -> "1.0.$runNumber"
-            stampVersion -> "1.0.$runNumber-dev"
-            isDevBuild -> "1.0.0-dev"
-            else -> "1.0.0"
+            stampVersion && buildChannel == "production" -> "$versionSeries.$runNumber"
+            stampVersion -> "$versionSeries.$runNumber-dev"
+            isDevBuild -> "$versionSeries.0-dev"
+            else -> "$versionSeries.0"
         }
 
         // The launcher label. With both copies on the phone the app drawer shows