feat: add isolated proposal changesets

schemas/project.schema.json

@@ -3,7 +3,7 @@
   "$id": "https://docforge.local/schema/project-v1.json",
   "title": "DocForge project descriptor",
   "type": "object",
-  "required": ["schema_version", "project_id", "title", "adapter", "sources", "derived", "graph"],
+  "required": ["schema_version", "project_id", "title", "adapter", "sources", "derived", "changesets", "graph"],
   "properties": {
     "schema_version": { "const": 1 },
     "project_id": { "type": "string", "pattern": "^[a-z0-9][a-z0-9._-]{1,127}$" },
@@ -27,6 +27,27 @@
       },
       "additionalProperties": false
     },
+    "changesets": {
+      "type": "object",
+      "required": ["root", "writers"],
+      "properties": {
+        "root": { "$ref": "#/$defs/relativePath" },
+        "writers": {
+          "type": "array",
+          "items": {
+            "type": "object",
+            "required": ["id", "families", "operations"],
+            "properties": {
+              "id": { "type": "string", "pattern": "^[a-z0-9][a-z0-9._-]{1,127}$" },
+              "families": { "type": "array", "minItems": 1, "uniqueItems": true, "items": { "type": "string", "minLength": 1 } },
+              "operations": { "type": "array", "minItems": 1, "uniqueItems": true, "items": { "enum": ["create", "update", "move", "delete"] } }
+            },
+            "additionalProperties": false
+          }
+        }
+      },
+      "additionalProperties": false
+    },
     "graph": {
       "type": "object",
       "required": ["allowed_relations"],