feat(rpc): expose snapshot, compare and restore for request versions

Three commands, all host-independent so the browser build answers them from
the same model layer as the desktop:

- models_snapshot_request, for the edit-session boundaries only the frontend
  can see. It takes a reason and nothing else — the caller does not decide
  whether anything changed, because content addressing already has.
- models_request_version, which returns a version and the live request's
  content together so they are guaranteed comparable, plus the same
  content-hash verdict the backend uses rather than a second opinion formed in
  TypeScript.
- models_restore_request_version.

The browser host also snapshots before its own send, since its send pipeline
is in TypeScript rather than in the shared crate.

Bindings regenerated with CI's `cargo test --all --features
yaak-app-client/wry`, which also drops a stale ImportSourceResource from the
rpc-schema copy and adds a missing ImportSource to the plugins copy.

crates/yaak-commands/src/models.rs

@@ -4,9 +4,10 @@
 use crate::error::Result;
 use crate::host::{Host, PluginHost};
 use yaak_models::models::{
-    AnyModel, GraphQlIntrospection, GrpcEvent, HttpRequestHeader, Settings, WebsocketEvent,
-    WorkspaceMeta,
+    AnyModel, GraphQlIntrospection, GrpcEvent, HttpRequestHeader, ModelVersion,
+    RequestVersionComparison, Settings, WebsocketEvent, WorkspaceMeta,
 };
+use yaak_models::versions::version_document;
 use yaak_models::queries::workspaces::default_headers;
 use yaak_rpc_schema::*;
 
@@ -45,6 +46,42 @@ pub async fn models_duplicate<H: Host>(host: H, req: ModelsDuplicateReq) -> Resu
     })?)
 }
 
+/// Capture the request's current content, from an edit-session boundary the
+/// frontend can see: switching away, losing focus, closing, or falling idle.
+///
+/// The frontend does not track whether anything actually changed — versions are
+/// content-addressed, so an unchanged request returns the version it already
+/// had and the trigger code stays a one-liner.
+pub async fn models_snapshot_request<H: Host>(
+    host: H,
+    req: ModelsSnapshotRequestReq,
+) -> Result<ModelVersion> {
+    Ok(host.db().snapshot_request_by_id(&req.request_id, req.reason)?)
+}
+
+/// A version and the live request side by side, for the diff and for deciding
+/// whether there is anything worth offering.
+pub async fn models_request_version<H: Host>(
+    host: H,
+    req: ModelsRequestVersionReq,
+) -> Result<RequestVersionComparison> {
+    let db = host.db();
+    let version = db.get_model_version(&req.version_id)?;
+    let current_document = version_document(&db.get_any_request(&version.model_id)?.to_value()?)?;
+    let differs = !db.request_matches_version(&version)?;
+    Ok(RequestVersionComparison { version, current_document, differs })
+}
+
+/// Returns the id of the request that was restored.
+pub async fn models_restore_request_version<H: Host>(
+    host: H,
+    req: ModelsRestoreRequestVersionReq,
+) -> Result<String> {
+    let source = host.update_source();
+    let restored = host.db().restore_request_version(&req.version_id, &source)?;
+    Ok(restored.id().to_string())
+}
+
 pub async fn models_websocket_events<H: Host>(
     host: H,
     req: ModelsWebsocketEventsReq,