fix(app): capture PCIe link / AER diagnostics at boot, not just on demand

pcie-nvidia-link.txt, pcie-nvidia-link-under-load.txt, and
kernel-aer-nvidia.txt only ever lived in supportBundleCommands, which
exclusively runs inside the on-demand "Download Support Bundle" web UI
action. The blackbox USB auto-sync worker never calls that function -
it only mirrors whatever CaptureTechnicalDump already wrote into the
live export tree at boot. So these three files were structurally
unreachable from a blackbox pull no matter how fresh the build was;
earlier analysis of a real blackbox misattributed their absence to
build/version drift instead.

Move the underlying scripts into shared exported constants
(platform.PCIeNvidiaLinkScript, PCIeNvidiaLinkUnderLoadScript,
KernelAERNvidiaScript) and add them to techDumpNvidiaCommands, so
CaptureTechnicalDump captures all three once at boot (bee-audit is
oneshot, so the ~8s bee-gpu-burn cost for the under-load sample is a
one-time boot cost, not a per-sync-cycle one) alongside the existing
nvidia-smi-* dumps. supportBundleCommands still re-runs the same
scripts on demand for a fresher sample - that's intentional, not a
duplicate to clean up.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

audit/internal/app/bundle_layout_test.go

@@ -0,0 +1,16 @@
+package app
+
+import "testing"
+
+func TestTechdumpBucketForPCIeLinkFiles(t *testing.T) {
+	cases := map[string]string{
+		"pcie-nvidia-link.txt":            "gpu",
+		"pcie-nvidia-link-under-load.txt": "gpu",
+		"kernel-aer-nvidia.txt":           "gpu",
+	}
+	for name, want := range cases {
+		if got := techdumpBucketFor(name); got != want {
+			t.Errorf("techdumpBucketFor(%q) = %q, want %q", name, got, want)
+		}
+	}
+}