Let the build agent run on the genesis document until its registry binds (hq issue 121, ADR 0336)

With npm-package-registry optional, the binding file the agent's environment
names may be absent, and mesh-builder failed every build on reading it. It now
reads the genesis document the installer seals at genesis's packages step when
no binding is present, prefers the binding when both are, and each build's log
says which it resolved from (§4). A build that needs the registry - a package,
an image naming .npmrc, TypeScript with an @novox/ dependency - on an agent with
neither is refused before anything is built or published, naming the machine,
the unbound requirement and gitea (§6); it never falls back to the public
registry. The captured catalogue moves to the mesh-catalog change it is judged
with.

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

@@ -76,6 +76,18 @@
       "path": "${dir:state}/settings.yml",
       "mode": "0600",
       "merge": "json",
+      "takes-settings": [
+        "general",
+        "brand",
+        "search",
+        "server",
+        "ui",
+        "outgoing",
+        "engines",
+        "plugins",
+        "categories_as_tabs",
+        "preferences"
+      ],
       "content": "{\n  \"use_default_settings\": true,\n  \"server\": {\n    \"secret_key\": \"${secret:secret}\",\n    \"base_url\": false,\n    \"limiter\": false,\n    \"image_proxy\": false,\n    \"public_instance\": false\n  },\n  \"search\": {\n    \"formats\": [\"html\", \"json\"]\n  },\n  \"valkey\": {\n    \"url\": \"valkey://valkey:6379/0\"\n  }\n}\n"
     },
     {