metal : per-device tuned (Q, NE) for flash-attn vec (#26570)

* metal : per-device tuned (Q, NE) for flash-attn vec (#25750)

* rebase Q-generic FA vec body from 01dc93607 (#23114)

* add 53 f16 (Q,NE) flash-attn vec instantiations (vec 80 -> 133)

* add FA vec (Q,NE) tuning table + dispatch wiring + SMEM cap fallback

* add  FA vec (Q,NE) perf sweep

* fill tuning result

* fold family table into a per-family representative SKU

* refactor tuning result format

* extend FA vec tuning to quantized KV caches

* sync fa vec tuner bucketing with runtime, use pointwise tuning regret

* update tuned table

* format and cleanup

* prefix fa_vec tuning procs with ggml_backend_metal_tuning_, drop unused fa_vec_override_active

* add device id -> token lookup for the offline tuning tool

* add ggml-metal-tuning skeleton

* add op-agnostic perf cell + median timing for the tuner

* add FA-vec graph build + tensor init to the tuner

* tools : add FA-vec (Q,NE) sweep, compression and table emit

* cool down and re-measure the dirty window on thermal drift

* test-backend-ops : replace the FA vec tune mode with a bounded (Q,NE) slice

* tools : document the Metal tuner, point the table comment at it

* abort on unknown KV type, single-source fa_vec_legal_ne

* cleanup

* honor -o in the FA vec (Q,NE) slice

* retune FA-vec (Q, NE) under a pointwise no-harm gate

* cont : add fa-vec tunings for M1 Pro, M2 Ultra, M5 Max

---------

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>

ggml/src/ggml-metal/ggml-metal-device.cpp

@@ -1,6 +1,7 @@
 #include "ggml-metal-device.h"
 
 #include "ggml-metal-impl.h"
+#include "ggml-metal-tuning.h"
 
 #include "ggml-impl.h"
 
@@ -1544,6 +1545,8 @@ ggml_metal_pipeline_with_params ggml_metal_library_get_pipeline_flash_attn_ext_v
         bool    has_bias,
         bool    has_scap,
         bool    has_kvpad,
+        int32_t nqpsg,
+        int32_t ne,
         int32_t nsg,
         int32_t nwg,
         bool    use_kv_f16,
@@ -1559,11 +1562,17 @@ ggml_metal_pipeline_with_params ggml_metal_library_get_pipeline_flash_attn_ext_v
 
     const char * type = use_kv_f16 ? "f16" : ggml_type_name(op->src[1]->type);
 
-    snprintf(base, 256, "kernel_%s_%s_dk%d_dv%d",
+    char qne_suffix[16] = {0};
+    if (!(nqpsg == 1 && ne == ggml_metal_tuning::fa_vec_baseline_ne(dk, dv))) {
+        snprintf(qne_suffix, sizeof(qne_suffix), "_q%d_ne%d", nqpsg, ne);
+    }
+
+    snprintf(base, 256, "kernel_%s_%s_dk%d_dv%d%s",
             "flash_attn_ext_vec",
             type,
             dk,
-            dv);
+            dv,
+            qne_suffix);
 
     snprintf(name, 256, "%s_mask=%d_sink=%d_bias=%d_scap=%d_kvpad=%d_ns10=%d_ns20=%d_nsg=%d_nwg=%d",
             base,