chore: publish safetensors NexaMat stack artifacts

cross_attention_contract.json

@@ -0,0 +1,34 @@
+{
+  "component": "nexa_mat_cross_attention_contract_v1",
+  "status": "interface_contract",
+  "purpose": "condition diffusion proposals and multimodal controller evidence on shared structure, text, task, and model-state lanes",
+  "lanes": [
+    {
+      "name": "structure_latent",
+      "producer": "encoder/v1/nexa_mat_V1_final.safetensors",
+      "consumer": "diffusion decoder and controller"
+    },
+    {
+      "name": "diffusion_state",
+      "producer": "decoder/diffusion_v1/final_checkpoint.safetensors",
+      "consumer": "controller ranking and evidence packet"
+    },
+    {
+      "name": "text_intent",
+      "producer": "Qwen controller tokens",
+      "consumer": "diffusion conditioning and reverse ranking"
+    },
+    {
+      "name": "evidence_context",
+      "producer": "retrieval/controller",
+      "consumer": "decision layer"
+    },
+    {
+      "name": "task_heads",
+      "producer": "SSB/battery-ion adapters",
+      "consumer": "reverse pool scoring and use-case constraints"
+    }
+  ],
+  "forward_flow": "constraints -> controller intent tokens -> diffusion proposals -> encoder plausibility scoring -> controller evidence and ranking",
+  "reverse_flow": "candidate pool -> encoder/task/evidence scoring -> optional decoder expansion -> controller rank/filter/explain"
+}