chore(release): v1.9.1-beta6

Version bump for the beta6 strobe artifact: VERSION, server package + lock, and
the Android client (versionName 1.9.1-beta6, versionCode 26 so OTA sees it as an
upgrade over beta5/25). Also removes two leftover untracked PiP test scratch files
(frontend/alert-overlay.html, frontend/overlay.js) from a prior session.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

VERSION

@@ -1 +1 @@
-1.9.1-beta5
+1.9.1-beta6

android/app/build.gradle.kts

@@ -11,8 +11,8 @@ android {
         applicationId = "com.remotedisplay.player"
         minSdk = 26
         targetSdk = 34
-        versionCode = 25
-        versionName = "1.9.1-beta5"
+        versionCode = 26
+        versionName = "1.9.1-beta6"
     }
 
     signingConfigs {

server/package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "screentinker",
-  "version": "1.9.1-beta5",
+  "version": "1.9.1-beta6",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "screentinker",
-      "version": "1.9.1-beta5",
+      "version": "1.9.1-beta6",
       "dependencies": {
         "@azure/msal-node": "^5.2.1",
         "archiver": "^7.0.1",

server/package.json

@@ -1,6 +1,6 @@
 {
   "name": "screentinker",
-  "version": "1.9.1-beta5",
+  "version": "1.9.1-beta6",
   "description": "ScreenTinker - Digital Signage Management Server",
   "main": "server.js",
   "scripts": {