Vulkan GPUs: real device names and selectable ordinals (rebase of #7356 onto #7476) (#7498)

* Vulkan GPUs: real device names and selectable ordinals

Rebases the durable half of #7356 onto the inference_gpu transport #7476
landed on main. Those two PRs solve an overlapping problem and disagree on
the data model, so merging #7356 as-is would ship two parallel Vulkan
device concepts with different index semantics. This keeps main's transport
and adds what #7356 had that #7476 does not.

- _vulkan_probe.py emits a 5th column, ggml's device description, sanitized
  for the tab protocol and UTF-8 safe. Reader tolerates 4- or 5-column
  output so an older probe still parses.
- llama_cpp gains _run_vulkan_probe (shared parse) and
  vulkan_device_inventory (names + is_igpu + real totals).
- get_vulkan_inference_gpu_info reports the real name and an explicit
  is_igpu instead of "Vulkan<i>" and a total == 0 guess.
- index_kind becomes "vulkan", not "relative", and gpu_ids picks are
  supported on Vulkan builds once the probe enumerated ordinals. The XPU ban
  no longer applies to them: a Vulkan pick is a ggml ordinal, not a torch-xpu
  index, so it works on an Intel host too.
- Frontend picker reads the Vulkan inventory as the pickable set.

Memory deliberately still comes from _get_gpu_memory, not the inventory.
That path applies _apply_igpu_host_reserve_mib and zeroes a shared total;
budgeting an APU off its raw shared total would hand out the whole machine's
RAM with no OS headroom. Identity is joined onto it by ordinal, so a probe
failure degrades to Vulkan<i> names with the memory readings intact.

Dropped from #7356 as superseded: validate_vulkan_gpu_ids (main's
resolve_requested_gpu_ids already rejects duplicates and
_resolve_gguf_gpu_ids_for_request already probes for existence), the
gguf_devices transport, and the iGPU budget fallback in 71619891e, which
main's aggregateGpuMemoryTotalGb handles better by counting a shared pool
once.

Also keeps #7356's removal of the late diffusion raise, so the graceful
gpu_ids drop stays reachable for a GGUF only classified as diffusion after
download. #7415's real guard, _reject_vulkan_diffusion_gpu_ids_before_
teardown, is untouched.

Verified on Windows + Strix Halo: backend Vulkan/GPU-selection suites at the
same 4 pre-existing failures as main, tests/studio 1671 passed with no new
failures, frontend typecheck clean. Hardware confirmation of the underlying
behavior is on #7356 from @Bebiv24 (RX 9070 XT + RX 480).

Co-authored-by: LeoBorcherding <borchborchmail@gmail.com>

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: LeoBorcherding <borchborchmail@gmail.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

studio/backend/tests/test_gpu_selection.py

@@ -427,14 +427,16 @@ class TestVisibleGpuUtilization(_GpuCacheResetMixin, unittest.TestCase):
 
         self.assertTrue(result["available"])
         self.assertEqual(result["backend"], "vulkan")
-        self.assertEqual(result["index_kind"], "relative")
+        # ggml Vulkan ordinals are the space `--device Vulkan<i>` pins, so they
+        # are selectable, unlike a torch-xpu relative ordinal.
+        self.assertEqual(result["index_kind"], "vulkan")
         self.assertEqual(result["parent_visible_gpu_ids"], [])
         self.assertEqual(
             result["devices"],
             [
                 {
                     "index": 0,
-                    "index_kind": "relative",
+                    "index_kind": "vulkan",
                     "visible_ordinal": 0,
                     "name": "Vulkan0",
                     "memory_total_gb": 8.0,