Judge tests that read another repository against what the check clones, never the desktop's checkout (issue 432)

Tests that read ../../../mesh-catalog or ../../../mesh-host gave a verdict
that depended on what sat beside the checkout: a stale or dirty sibling
failed them on a desktop, and a missing one skipped them unseen. They now
read the clone the build seat puts in MESH_CHECK_BESIDE, failing when it is
absent there, and elsewhere a copy captured at a named commit.

The skip had hidden that the builder test read a module retired by ADR 0190.
The systemd reading test no longer counts the machine's own environment.d.

testdata/beside/mesh-catalog/modules/dmenu/module.json.captured

@@ -0,0 +1,33 @@
+{
+  "module": "dmenu",
+  "version": "1",
+  "capabilities": [
+    "package-manager"
+  ],
+  "tools": [
+    "dmenu_menu",
+    "dmenu_session"
+  ],
+  "resources": [
+    {
+      "id": "package",
+      "type": "package",
+      "package": "dmenu"
+    }
+  ],
+  "build": {
+    "artifacts": [
+      {
+        "name": "tools",
+        "kind": "bundle",
+        "language": "go",
+        "system": "arch",
+        "from": "cmd/dmenu-tools",
+        "binary": "dmenu-tools",
+        "loads": [
+          "dmenu-tools"
+        ]
+      }
+    ]
+  }
+}