PR #267

Title: Fix storage folder handling

Source PR: WinNative-Emu/WinNative#267
Source branch: fix-storage-folder-handling
Source commit: b65915ad36a1acd8de15b3495f8e9a21c9ae1139
Build workflow run: https://github.com/MaxsTechReview/WinNative/actions/runs/24926203274

What This PR Is About

Adds shared Android file picker and folder picker contracts that prefer normal device storage roots.
Validates selected folders are resolvable and writable before saving them for stores, shortcuts, containers, and game installs.
Releases stale persisted tree URI permissions only after all active folder preferences are available.
Keeps existing folder grants when persistable permission capture fails for a newly selected folder.
Aligns Epic and GOG custom install folder behavior with Steam when the selected folder already matches the game folder.
Avoids storing pseudo tree URI paths when folder URI resolution fails.
Keeps Steam direct launches, ColdClient setup, and Steamless unpacking on the current service-resolved install folder when custom install paths change.
Refreshes stale Steam shortcut executable metadata when a valid executable is found in the current install folder.
Adds writable-directory checks before Steam, Epic, and GOG downloads create install markers.
Fixes CI compile errors from the tree URI helper expression body and missing Activity import.
git diff --check passed with only existing CRLF warnings.
Gradle compile was not run locally because java is not on PATH and JAVA_HOME is unset.

Built from source commit b6591.