[FEAT] Support OpenRouter

[hqc8848]

Is your feature request related to a problem? Please describe.
I use OpenRouter for LLM models, but there are no option for choosing OpenRouter as LLM provider.

Describe the solution you'd like
Add option for choosing OpenRouter as LLM provider.

Describe alternatives you've considered
I wanted to use local Ollama models for instead but my 8GB RAM and 256GB disk say no.

Additional context
None.

[PhantomInTheWire]

we have #126 you could push for it there

[dirm02]

I second this feature! my openrouter API keys are invalid :(

[PhantomInTheWire]

@dirm02 this project seems to be dead use cheating daddy