fix(ui): label Portable Chrome as PSP theme

[papi-ux]

Summary

• Renames the visible Nova theme option from Portable Chrome to PSP / Portable Chrome
• Keeps the stable stored value portable_chrome so existing installs and tests remain compatible
• Updates settings summary, label resources, changelog, and regression tests

Test Plan

• RED: theme label tests failed while resources still said Portable Chrome
• ./gradlew testDebugUnitTest --tests com.papi.nova.ui.NovaThemeManagerTest --tests com.papi.nova.ui.NovaThemeResourcesTest
• ./gradlew testDebugUnitTest assembleRootDebug lintRootDebug
• aapt dump --values resources app/build/outputs/apk/root/debug/app-root-arm64-v8a-debug.apk confirmed PSP / Portable Chrome in nova_theme_names and nova_theme_portable_chrome_label
• adb install -r -d -g app/build/outputs/apk/root/debug/app-root-arm64-v8a-debug.apk on Retroid Pocket 6
• run-as prefs verify nova_theme=portable_chrome
• monkey launch confirmed com.papi.nova.root.debug/com.papi.nova.ui.NovaLibraryActivity resumed