T YouTube Zversion test-zversion-4

Zversion 4 test build from stable v1.0.1 at commit a2c4917. Shorts: fixes the real cause of the stuck plain arrow - a SECOND view with the same reel_back_button id (reel_player_back_button.xml) still shipped quantum_ic_arrow_back_white_24, so findViewById() could hand the player the arrow instead of the brand loop; both layouts now carry the 8s T YouTube loop, and onWindowFocusChanged restarts the AnimationDrawable once attached so it can no longer freeze on frame 0. Fullscreen watermark: now smaller (14sp, 32dp) and lower - anchored to the bottom of the control row below the scrubber line - and hidden in sync with the controls via onVisibilityChanged (fires when the view OR an ancestor changes visibility). Downloads: stable v1.0.1's proven checkSelectedDownload is restored unchanged (Zversion 3's rewrite had inverted conditionals and broke even the first download), plus two surgical changes: an existing file with no mission and a finished duplicate both fall through to createUniqueFile() and start downloading immediately - no taps, no overwrite - while pending/running missions only show a cancel-only dialog and are never overwritten; the filename still starts with the real video title. About screen shows '21.20.402 (Zversion 4)' so the installed build is easy to identify. Package, version code and AOSP testkey signature are unchanged, so it installs over v1.0.1 with data intact. Not a stable release - stable v1.0.1 remains the recommended download. See T-YouTube-Zversion-TEST-README.txt for the checklist.