Load the runtime that fits the GPU, not the first one found

A runtime carries one vendor's providers, only one loads per process,
and a device can now hold several: the package's OpenVINO or WebGPU
build, a CUDA build the user fetched, the distribution's ROCm build.
`api::install` opens each it finds, lists its providers with
GetAvailableProviders, and installs the one scoring highest against the
GPUs `hardware::detect` reads from files — a vendor rung on its own
vendor's GPU above OpenVINO on an Intel one above the generic WebGPU
rung above a CPU-only build. Equal scores keep the old first-found
order, and DARKROOM_ORT_DIR still wins outright. The losers stay mapped
rather than unloaded.

The Linux fingerprint now names the OpenCL drivers too, so installing
Intel's re-probes. `ladder` takes DARKROOM_ORT_DIRS to show the choice.

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

@@ -391,19 +391,35 @@ fn providers_beside(runtime: &Path) -> String {
 
 #[cfg(target_os = "linux")]
 fn device_identity() -> String {
-    // 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.
+    // The NVIDIA driver's version line, the ROCm release the AMD stack came
+    // from (`rocm-core` writes it; the kernel driver has no version of its
+    // own), and the OpenCL drivers registered — OpenVINO reaches the GPU
+    // through one, and installing Intel's is what makes the Iris Xe a rung.
+    let mut parts = Vec::new();
     if let Some(line) = std::fs::read_to_string("/proc/driver/nvidia/version")
         .ok()
         .and_then(|s| s.lines().next().map(str::to_string))
     {
-        return line;
+        parts.push(line);
     }
     if let Ok(rocm) = std::fs::read_to_string("/opt/rocm/.info/version") {
-        return format!("rocm {}", rocm.trim());
+        parts.push(format!("rocm {}", rocm.trim()));
+    }
+    let mut icds: Vec<String> = std::fs::read_dir("/etc/OpenCL/vendors")
+        .into_iter()
+        .flatten()
+        .filter_map(|e| e.ok())
+        .map(|e| e.file_name().to_string_lossy().into_owned())
+        .collect();
+    icds.sort();
+    if !icds.is_empty() {
+        parts.push(format!("opencl {}", icds.join(" ")));
+    }
+    if parts.is_empty() {
+        "no nvidia driver, no rocm, no opencl".into()
+    } else {
+        parts.join("; ")
     }
-    "no nvidia driver, no rocm".into()
 }
 
 #[cfg(target_os = "android")]
@@ -418,7 +434,7 @@ fn device_identity() -> String {
 }
 
 #[cfg(target_os = "android")]
-fn system_property(name: &str) -> String {
+pub(crate) fn system_property(name: &str) -> String {
     extern "C" {
         fn __system_property_get(
             name: *const std::ffi::c_char,