nx_motion_video_gate.nx

nx_motion_video_gate.nx -- prove the S3 loop end-to-end: BUILD a move (data) -> pose the rig via FK per frame -> render the articulated figure -> encode a sovereign ANIMATED PNG = "show the move in a VIDEO". Asserts: T1 the .png is a real APNG (signature + acTL/fcTL/fdAT/IEND + acTL num_frames == N) T2 MOTION happened (frame 0 checksum != mid-frame checksum -- the figure actually moved, not a static loop) T3 a driven JOINT moved (right wrist world-Y spans a real range across the clip = true FK articulation) T4 two DIFFERENT moves (wave vs kick) produce DIFFERENT poses at the same time (the library varies, like t2mesh) Writes knowledge/nx_motion_wave.png (APNG, browser-playable) + knowledge/nx_motion_frame0.png (still, eyeball). license_tier: ORIGINAL expect_exit: 0