Pin edit_target in the page's client surface (improvise-au6c)

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VdfEGXA7aJ6ftMsCc9PJze

web/tests/bundle/wasm_surface.test.js

@@ -80,6 +80,9 @@ test("the page still reaches the client through a handful of calls", () => {
       "click_page_item",
       "click_tile",
       "click_view",
+      // improvise-2wu3/0j0f: what an editor edits, captured when it opens, so
+      // its commit names that record at that version and not a position.
+      "edit_target",
       "on_frame",
       "on_key_event",
       "render_model",