feat: advance local-first workspace checklist

- add admin access-policy UI and local access control surfaces

- add local markdown conflict resolution UI and smoke coverage

- add ACP local agent changed-files audit scaffold and read-only write guard

- document current P0-P2 checklist progress and verification evidence

rust/crates/core-protocol/src/page_aggregate.rs

@@ -139,6 +139,7 @@ mod tests {
         assert_eq!(body.block_projection_version, 0);
         assert_eq!(body.block_document, json!(null));
         assert_eq!(body.projection_source, "");
+        assert_eq!(body.file_version, json!(null));
     }
 }
 
@@ -149,6 +150,8 @@ pub struct PageBody {
     pub revision: Value,
     pub conflict_detection_key: Value,
     #[serde(default)]
+    pub file_version: Value,
+    #[serde(default)]
     pub block_document: Value,
     #[serde(default)]
     pub block_projection_version: u32,