fix(nesdoctor): fall back to the SoC name on Apple Silicon, and print raw probes

The macOS arm added in the previous commit did not change anything -- the
runner still reported `gpu=unknown`. Checked rather than assumed, which is the
only reason it is known.

Two possible causes and no way to choose between them from here: either the
`system_profiler SPDisplaysDataType` parsing is wrong, or that machine is a
headless virtual Mac with no display adapter to enumerate at all, in which case
`unknown` was the correct answer and there is nothing to fix. The second is
likely and the first is not ruled out.

So, rather than guessing again: on an arm64 Mac the GPU *is* the SoC, so the
chip name is a true and useful answer even with no display attached.
`sysctl -n machdep.cpu.brand_string` works headless and yields
"Apple M1 (integrated)". Intel Macs get no fallback, because there the GPU may
be integrated or discrete and a guess would be wrong rather than coarse.

And the CI step now dumps the **raw** output of each platform's probes --
`system_profiler`, `Get-CimInstance Win32_VideoController`, `Get-PSDrive`,
`df -Pk`, `/sys/class/drm` -- into its own log group. A field that comes back
empty can then be told apart from a parser that is wrong, which is exactly the
distinction that cost this round trip. All of it is `|| true`: the step exists
for looking, and a probe that misbehaves on a runner must never fail a release.

apps/nesdoctor/src/sys.rs

@@ -293,6 +293,27 @@ fn gpus() -> Vec<Gpu> {
                 });
             }
         }
+        // Fallback for Apple Silicon, where the GPU *is* the SoC.
+        //
+        // The CI runner is a headless virtual Mac and still reported
+        // `gpu=unknown` after the parser above was added, which means either
+        // the parser is wrong or that machine genuinely has no display adapter
+        // to enumerate. Both are plausible and the second is likely, so rather
+        // than guess: on an arm64 Mac the integrated GPU is part of the chip,
+        // so the chip name is a true and useful answer even with no display
+        // attached.
+        if gpus.is_empty() && cfg!(target_arch = "aarch64") {
+            if let Some(soc) = sh("sysctl", &["-n", "machdep.cpu.brand_string"]) {
+                let soc = soc.trim();
+                if !soc.is_empty() {
+                    gpus.push(Gpu {
+                        name: format!("{soc} (integrated)"),
+                        vendor: Some("Apple".into()),
+                        render_node: None,
+                    });
+                }
+            }
+        }
         return gpus;
     }
     #[cfg(not(any(target_os = "linux", windows, target_os = "macos")))]