chore(release): 4.9.1

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PpMNz7Xnv4trztaPfuSBu

Author: SoxiaLiSA

app/build.gradle

@@ -86,8 +86,8 @@ android {
         applicationId "ceui.pixiv"
         minSdkVersion 24
         targetSdkVersion 36
-        versionCode 42300
-        versionName "4.9.0"
+        versionCode 42400
+        versionName "4.9.1"
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
         ndk {
             // Production remains arm64-only. CI can request x86_64 so instrumented tests run on