feat: add AI_EMBEDDING_SUPPORTS_MRL env var to decouple pgvector dimensions from model API (#2079)

Some embedding models don't accept a `dimensions` parameter. This adds
an optional env var that controls whether the dimension is sent to the
model API, while always using it for pgvector indexing. Preset models
have this handled automatically; the env var allows explicit override
for custom models.

apps/client/package.json

@@ -25,7 +25,7 @@
     "@tabler/icons-react": "^3.40.0",
     "@tanstack/react-query": "5.90.17",
     "alfaaz": "^1.1.0",
-    "axios": "^1.13.6",
+    "axios": "1.13.6",
     "blueimp-load-image": "^5.16.0",
     "clsx": "^2.1.1",
     "emoji-mart": "^5.6.0",