rocky-vulkan-llama: skeleton — deps, root-cause diagnosis, llama.cpp submit patch

Documents the RK3588 Mali-G610 GPU-prefill stack (panthor + panvk + llama.cpp Vulkan),
the panvk ub64 OOM blocker, and collects the ggml-vulkan tunable-submit patch. Mesa panvk
fix pending root-cause confirmation (see docs/root-cause.md).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

patches/llama.cpp-0001-vk-tunable-submit-thresholds.patch

@@ -0,0 +1,29 @@
+diff --git a/ggml/src/ggml-vulkan/ggml-vulkan.cpp b/ggml/src/ggml-vulkan/ggml-vulkan.cpp
+index 0a79310..8732cf9 100644
+--- a/ggml/src/ggml-vulkan/ggml-vulkan.cpp
++++ b/ggml/src/ggml-vulkan/ggml-vulkan.cpp
+@@ -14684,11 +14684,14 @@ static ggml_status ggml_backend_vk_graph_compute(ggml_backend_t backend, ggml_cg
+     // (and scaled down based on model size, so smaller models submit earlier).
+     // Also submit at least every 100 nodes, in case there are workloads without as much matmul.
+     int nodes_per_submit = 100;
++    if (const char* e = getenv("GGML_VK_NODES_PER_SUBMIT")) { nodes_per_submit = atoi(e); }
+     int submitted_nodes = 0;
+     int submit_count = 0;
+     uint64_t mul_mat_bytes = 0;
+     uint64_t total_mul_mat_bytes = 0;
+-    uint64_t mul_mat_bytes_per_submit = std::min(uint64_t(100*1000*1000), ctx->last_total_mul_mat_bytes / 40u);
++    uint64_t mul_mat_bytes_cap = 100*1000*1000;
++    if (const char* e = getenv("GGML_VK_MAX_MUL_MAT_BYTES_PER_SUBMIT")) { mul_mat_bytes_cap = strtoull(e, nullptr, 10); }
++    uint64_t mul_mat_bytes_per_submit = std::min(mul_mat_bytes_cap, ctx->last_total_mul_mat_bytes / 40u);
+     for (int i = 0; i < cgraph->n_nodes; i++) {
+         if (first_node_in_batch) {
+             submit_node_idx = i;
+@@ -14925,7 +14928,7 @@ static ggml_status ggml_backend_vk_graph_compute(ggml_backend_t backend, ggml_cg
+             submitted_nodes = 0;
+             mul_mat_bytes = 0;
+             if (submit_count < 3) {
+-                mul_mat_bytes_per_submit *= 2;
++                mul_mat_bytes_per_submit = std::min(mul_mat_bytes_per_submit * 2, mul_mat_bytes_cap);
+             }
+             submit_count++;
+         }