feat: webui use querystring as settings

[sigoden]

After this PR merged, User can use querystring to set parameters

LLM Playground

http://192.168.8.10:8000/playground?model=openai%3Agpt-4o-mini&role=%25code%25&temperature=0&top_p=0

URLSearchParams {
    'model' => 'openai:gpt-4o-mini',
    'role' => '%code%',
    'temperature' => '0',
    'top_p' => '0' },

LLM Arena

http://192.168.8.10:8000/arena?models=openai%3Agpt-4o-mini%2Copenai%3Agpt-4o

URLSearchParams { 'models' => 'openai:gpt-4o-mini,openai:gpt-4o' },

[sigoden]

Partial solve #808: set role within the URL