Add the MIGraphX rung for AMD GPUs

Measured on a Radeon RX 7900 XT against Arch's onnxruntime-rocm 1.29
(docs/inference.md §1.3): MIGraphX fp16 runs the detectors at 2.4–3.4 ms
against 10–58 ms on the CPU provider, the inpainter at 8 ms against 514,
with a 15–135 s compile per graph the first time and under a second from
its cache after. A compiling rung on TensorRT's terms, wired the same way.

The ROCm execution provider is gone (removed in ONNX Runtime 1.23), so the
AMD ladder is MIGraphX then the CPU, with no non-compiling rung between.

MIGraphX is registered through the runtime's generic key/value entry
point rather than ort's builder: 1.29 reads the legacy options struct for
its precision flags only, and the compiled-program cache directory
(`migraphx_model_cache_dir`) only travels the generic way. The provider's
cache key omits the precision, so f32 and fp16 programs get their own
directories. The probe fingerprint now includes the provider libraries
beside the runtime and the ROCm version, since a distribution's CPU and
ROCm builds are the same file at the same path.

`status().failed` reports only the rungs above the selection, so an AMD
desktop's About line says why MIGraphX won rather than that the NVIDIA
providers are not in the build.

Two examples: `ep_probe` times each provider cold and from cache, and
`ladder` drives `init` as the app does to watch the first-run sequence.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

core/dr-inference-engine/src/probe.rs

@@ -16,8 +16,11 @@ use crate::{api::Runtime, state, Cache, Config, Form, Role, Rung};
 fn ladder(ceiling: Option<Rung>) -> Vec<Rung> {
     #[cfg(target_os = "android")]
     let all = [Rung::Hexagon];
+    // A desktop has one vendor's GPU; the other vendor's providers are
+    // "not enabled in this build" or a library that fails to load, and
+    // either answer arrives in milliseconds.
     #[cfg(not(target_os = "android"))]
-    let all = [Rung::TensorRt, Rung::Cuda];
+    let all = [Rung::TensorRt, Rung::Cuda, Rung::MiGraphX];
     all.into_iter()
         .filter(|r| ceiling.is_none_or(|c| *r <= c))
         .collect()
@@ -206,15 +209,22 @@ fn first_line(s: &str) -> String {
     line[start..].chars().take(200).collect()
 }
 
-/// Everything a change of which should re-probe: the runtime and where it
-/// came from, this crate, the platform, the driver or SoC, and the models.
+/// Everything a change of which should re-probe: the runtime, where it
+/// came from and which providers sit beside it, this crate, the platform,
+/// the driver or SoC, and the models.
 fn fingerprint(runtime: &Runtime, cfg: &Config) -> String {
     let mut parts = vec![
         format!("engine {}", env!("CARGO_PKG_VERSION")),
         format!("{} {}", std::env::consts::OS, std::env::consts::ARCH),
         match runtime {
             Runtime::Tract => "tract".to_string(),
-            Runtime::OnnxRuntime { path, version } => format!("ort {version} {}", path.display()),
+            Runtime::OnnxRuntime { path, version } => {
+                format!(
+                    "ort {version} {} [{}]",
+                    path.display(),
+                    providers_beside(path)
+                )
+            }
         },
         device_identity(),
     ];
@@ -237,13 +247,41 @@ fn fingerprint(runtime: &Runtime, cfg: &Config) -> String {
     parts.join("\n")
 }
 
+/// The `libonnxruntime_providers_*.so` files in the runtime's directory.
+/// A distribution's CPU-only and ROCm builds are the same version at the
+/// same path; the provider libraries beside them are what differs.
+fn providers_beside(runtime: &Path) -> String {
+    let Some(dir) = runtime.parent() else {
+        return String::new();
+    };
+    let mut names: Vec<String> = std::fs::read_dir(dir)
+        .into_iter()
+        .flatten()
+        .filter_map(|e| e.ok())
+        .filter_map(|e| e.file_name().into_string().ok())
+        .filter(|n| {
+            n.starts_with("libonnxruntime_providers_") || n.starts_with("onnxruntime_providers_")
+        })
+        .collect();
+    names.sort();
+    names.join(" ")
+}
+
 #[cfg(target_os = "linux")]
 fn device_identity() -> String {
-    // The NVIDIA driver's version line; absent means no NVIDIA driver.
-    std::fs::read_to_string("/proc/driver/nvidia/version")
+    // The NVIDIA driver's version line, or the ROCm release the AMD stack
+    // came from (`rocm-core` writes it; the kernel driver has no version
+    // of its own). Absent means neither.
+    if let Some(line) = std::fs::read_to_string("/proc/driver/nvidia/version")
         .ok()
         .and_then(|s| s.lines().next().map(str::to_string))
-        .unwrap_or_else(|| "no nvidia driver".into())
+    {
+        return line;
+    }
+    if let Ok(rocm) = std::fs::read_to_string("/opt/rocm/.info/version") {
+        return format!("rocm {}", rocm.trim());
+    }
+    "no nvidia driver, no rocm".into()
 }
 
 #[cfg(target_os = "android")]