Keep the declarations the controller composed before placement moved (issue 651)

Written by the integration branch's controller at bfc79c6 from the seed of
TestADeclarationIsTheSameAfterPlacementMoves.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

cmd/mesh-controller/testdata/placement-moved/anchor.json

@@ -0,0 +1,46 @@
+[
+  {
+    "id": "found.server",
+    "image": "registry.invalid:5000/library@sha256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+    "networks": [
+      "predecessor_default"
+    ],
+    "type": "container"
+  },
+  {
+    "id": "library.access-storage/downloads",
+    "mode": "read",
+    "path": "/storage/downloads",
+    "type": "access"
+  },
+  {
+    "id": "library.access-storage/media/series",
+    "mode": "read",
+    "path": "/storage/media/series",
+    "type": "access"
+  },
+  {
+    "id": "library.config",
+    "mode": "0750",
+    "owner": "1001:2000",
+    "path": "/var/lib/library/config",
+    "type": "directory"
+  },
+  {
+    "content": "{\n  \"accesses\": {\n    \"downloads\": \"/storage/downloads\",\n    \"series\": \"/storage/media/series\"\n  },\n  \"log\": \"warn\",\n  \"places\": {\n    \"config\": {\n      \"owner\": \"1001:2000\",\n      \"path\": \"/var/lib/library/config\"\n    }\n  },\n  \"workers\": 4\n}\n",
+    "id": "library.runtime-config",
+    "mode": "0640",
+    "path": "/var/lib/library/config/runtime.json",
+    "type": "file"
+  },
+  {
+    "id": "library.server",
+    "image": "registry.invalid:5000/library@sha256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+    "type": "container",
+    "volumes": [
+      "/var/lib/library/config:/config",
+      "/storage/media/series:/series",
+      "/storage/downloads:/downloads:ro"
+    ]
+  }
+]

cmd/mesh-controller/testdata/placement-moved/laptop.json

@@ -0,0 +1,37 @@
+[
+  {
+    "id": "library.access-home/media/series",
+    "mode": "read",
+    "path": "/home/media/series",
+    "type": "access"
+  },
+  {
+    "id": "library.access-storage/downloads",
+    "mode": "read",
+    "path": "/storage/downloads",
+    "type": "access"
+  },
+  {
+    "id": "library.config",
+    "mode": "0750",
+    "path": "/var/lib/library/config",
+    "type": "directory"
+  },
+  {
+    "content": "{\n  \"accesses\": {\n    \"downloads\": \"/storage/downloads\",\n    \"series\": \"/home/media/series\"\n  },\n  \"log\": \"warn\"\n}\n",
+    "id": "library.runtime-config",
+    "mode": "0640",
+    "path": "/var/lib/library/config/runtime.json",
+    "type": "file"
+  },
+  {
+    "id": "library.server",
+    "image": "registry.invalid:5000/library@sha256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+    "type": "container",
+    "volumes": [
+      "/var/lib/library/config:/config",
+      "/home/media/series:/series",
+      "/storage/downloads:/downloads:ro"
+    ]
+  }
+]