Add coverart nodes and mesh-to-mesh links

{
  "backend": {
    "author": {
      "email": "drschwabe@fastmail.com",
      "name": "Derrick Schwabe",
      "time": 1787966043
    },
    "commit": "git:sha1:52b58599a44e3baac1c76793ba9b1cba527338e2",
    "committer": {
      "email": "drschwabe@fastmail.com",
      "name": "Derrick Schwabe",
      "time": 1787966069
    },
    "manifest": "mmm-manifest:sha256:0018c2aac1e539afe52072f58e822c059f0a05224492f936b338c823754a2149",
    "message": "Add coverart nodes and mesh-to-mesh links\n\nA link is a new kind of value naming another mesh file; a coverart node is\na link with artwork on it, chosen from any image inside the linked mesh.\nDouble-click follows it in this window, middle-click in a new tab,\nright-click opens the picker.\n\nThis needed meshes to become addressable: a tab now names its mesh in\n?mesh=, which /load and /save both take, so several meshes can be open at\nonce without saving over each other.",
    "objectFormat": "sha1",
    "parents": [
      "git:sha1:9d85d806c681ed93e4052a2518a5ff93c26104b4"
    ],
    "ref": "refs/heads/master",
    "summary": "Add coverart nodes and mesh-to-mesh links",
    "tree": "git:sha1:f16ffff7a00bb82af691f613fea59f57f61eed50",
    "type": "git"
  },
  "issuedAt": "2026-08-29T01:16:31.995Z",
  "previous": "mmm-revision:sha256:2996362ec27d51bceb5e0c8f5ca7ba2cf80b11f5a34d2cc63bae1063bdc20d24",
  "project": "mmm1np06566gf6u8fpyj84u2emf25l98qad36700d2nlep6jzqdknp8qkyd3xu",
  "protocol": "mmm/0-alpha",
  "sequence": 10,
  "type": "mmm/revision"
}