Fix 3D texture corruption and stuck/dead-key input bugs

Stale GL_UNPACK state in gl4es and a missing pre-release GPU sync
caused diagonal-banded corruption in the 3D view. Synthetic key
press/release must track the real controller button or touch down/up
edges, not fire together in one call - fixes a typed movement key
sticking forever, then a follow-up that had silently broken A-button
jump and on-screen keyboard arrow keys. Also adds force-rebuild.sh for
the known stageEngine stale-cache issue.

android/app/src/main/cpp/xr_overlay.c

@@ -427,6 +427,15 @@ bool xr_overlay_render_and_build_layer(XrOverlay *overlay, XrCompositionLayerQua
                             overlay->width, 0, GL_COLOR_BUFFER_BIT, GL_LINEAR);
     real_glBindFramebuffer(GL_READ_FRAMEBUFFER, (GLuint)prevReadFbo);
 
+    // Without this, nothing here waits for the blit to actually finish on
+    // the GPU before xr_swapchain_release() hands the image back to the
+    // compositor - glBlitFramebuffer only queues the copy. A cross-process
+    // consumer reading the image before the driver has finished writing it
+    // is a textbook source of the diagonal-banded/torn corruption seen on
+    // device (see xr_swapchain_acquire()'s counterpart in OpenGL.cc, which
+    // had the same gap).
+    glFinish();
+
     xr_swapchain_release(overlay->instance, &overlay->swapchain);
 
     memset(out_quad, 0, sizeof(*out_quad));