chore: update webapp to repo-review 1.2.0 (#806)

Bump the embedded repo-review-webapp anywidget and the repo-review dep
to 1.2.0. The 1.2.0 webapp now runs Pyodide in a web worker, but this is
internal to the bundle; the anywidget embed API (url_sync/deps, export
path) is unchanged, so only version pins need updating.

Assisted-by: ClaudeCode:claude-opus-4.8

Author: henryiii

docs/pages/guides/repo_review.md

@@ -18,11 +18,11 @@ pipx run 'sp-repo-review[cli]' <path to repo>
 ---
 
 <!-- rumdl-disable-next-line MD034 -->
-:::{anywidget} https://cdn.jsdelivr.net/npm/repo-review-webapp@1.1.3/dist/repo-review-anywidget.mjs
+:::{anywidget} https://cdn.jsdelivr.net/npm/repo-review-webapp@1.2.0/dist/repo-review-anywidget.mjs
 {
   "url_sync": true,
   "deps": [
-    "repo-review~=1.1.0",
+    "repo-review~=1.2.0",
     "sp-repo-review==2026.04.04",
     "validate-pyproject[all]~=0.25.0",
     "validate-pyproject-schema-store==2026.04.03",