index.html was served with `max-age=31536000, immutable` like the hashed assets, but its name is stable while its contents change every build, so a cached copy pins the UI to an old build. It now revalidates via its existing ETag, which keeps the 304 for unchanged builds.
* webui: load the model selected via ?model=
Opening the WebUI with ?model= selects the model but doesn't load it. The load only starts when you send your first message, so you wait for it then.
This loads it as soon as the page opens, while you're still typing your prompt. It's what the model dropdown already does, and it isn't awaited, so the UI still works while the model loads.
This is the path the Llama macOS app uses to open the WebUI, so it's a common way in.
* webui: gate the load behind ?load=true
Loading on landing is opt-in, so a plain ?model= link behaves as before and doesn't allocate memory on its own.
* webui: name the chat URL params
Collects the query params the chat routes read into a URL_PARAMS constant, instead of repeating the literals across three files. NEW_CHAT_PARAM folds into it.
