Fix DLSS quality-change corruption and frame completion ordering

- Reprepare enc3 weights each launch to avoid stale caches after feature recreation
- Require per-slot input markers before evaluating recorded frames
- Advance split-frame timelines only through completed frames
- Add cancellation and readiness tests plus recreation consistency checks
- Update architecture and native kernel documentation

ref #8

kernels/m/rrlite_enc3_tube_4x4.hip

@@ -3,6 +3,9 @@
 #define SWIN_F32ACC
 #define SWIN_MAX_VGPR 192
 #define SWIN_MLP_R(NW) 2
-#define SWIN_PREP_SLOTS 8 // one weight image per tube block (six per frame)
+// NGX can recycle a weights address for another tube block after feature
+// recreation. Address-only caching then serves stale packed weights. Prepare
+// each launch; the default single image is sufficient on the launch stream.
+#define SWIN_PREP_KEY_AT 0
 #include "swin_block.h"
 SWIN_MODULE_W(rrlite_enc3_tube_4x4, 128, 4, 8, 0, true, TubeParams, 0)