feat(chat): save and view chat history — admin-only saved_chats, History page, open-a-chat return

tests/unit/test_steering_toggle_removal.py

@@ -22,8 +22,8 @@ ASSETS = FRONTEND / "assets"
 
 HEADER_JS = ASSETS / "header.js"
 
-#: All six pages carry the shared header block (phase 34's five pages +
-#: phase 35's git-sources page).
+#: All seven pages carry the shared header block (phase 34's five pages
+#: + phase 35's git-sources page + phase 50's History page).
 PAGES = (
     FRONTEND / "index.html",
     FRONTEND / "sources.html",
@@ -31,6 +31,7 @@ PAGES = (
     FRONTEND / "git-sources.html",
     FRONTEND / "login.html",
     FRONTEND / "tuning.html",
+    FRONTEND / "history.html",
 )