Add personal notes, DeepSearch history, backup offload, and gateway auth throttling

Also streamline the top navigation: drop the Tools dropdown, make Quizzes
and Battles icon-only entries, and remove the Workspace, Containers and
Editor entry points from the project detail page.

tests/unit/services/openai_gateway/routing.py

@@ -267,6 +267,32 @@ def test_embed_route_and_kind_isolation(local_db):
         _cleanup(["utemb"], ["ut-embed"])
 
 
+def test_embed_overlay_blank_provider_key_preserves_top_level_key(local_db):
+    r.provider_store.set(
+        r.ProviderIn(
+            name="utemblank",
+            base_url="https://emb.example/v1/chat/completions",
+            api_key="",
+        )
+    )
+    r.model_store.set(
+        r.ModelRouteIn(
+            source_model="ut-embed-blank",
+            provider="utemblank",
+            target_model="vendor/embed",
+            kind="embed",
+        )
+    )
+    try:
+        base_cfg = {"gateway_embed_key": "top-level-fallback-key"}
+        overlay = r.embed_overlay("ut-embed-blank", base_cfg)
+        assert "gateway_embed_key" not in overlay
+        merged = {**base_cfg, **overlay}
+        assert merged["gateway_embed_key"] == "top-level-fallback-key"
+    finally:
+        _cleanup(["utemblank"], ["ut-embed-blank"])
+
+
 def test_inactive_route_ignored(local_db):
     r.model_store.set(
         r.ModelRouteIn(