chore: prepare release v0.6.0-beta (versionCode 58 -> 59)

Bump versionName to v0.6.0-beta and versionCode to 59. The OTA notes
(controller/ci/ota-release-notes.md) already carry the matching v0.6.0-beta entry,
so tagging v0.6.0-beta will build + publish update.json + APKs to k2go-download.

Author: luisguzman-adfa

controller/app/build.gradle

@@ -38,12 +38,12 @@ android {
 
         // 3. Version Control (OTA)
         // NOTE: With splits enabled, this number will be multiplied by 10 (e.g. 50 -> 500, 501, 502)
-        versionCode 58
+        versionCode 59
         // Dynamic version suffix: CI passes -PversionSuffix explicitly; local builds fall back to
         // the git short SHA (ADFA-4787) so any installed APK is traceable to its commit.
         def ciSuffix = project.hasProperty('versionSuffix') ? project.property('versionSuffix')
                 : (project.ext.gitSha ? "-${project.ext.gitSha}" : "")
-        versionName "v0.5.1-beta${ciSuffix}"
+        versionName "v0.6.0-beta${ciSuffix}"
         buildConfigField "String", "GIT_SHA", "\"${project.ext.gitSha}\""
 
         setProperty("archivesBaseName", "$applicationId-$versionName")