[Feature] Allow direct numeric input for reasoning budget when using `budget_slider`

When reasoningSlider.type is set to budget_slider, the UI only allows selecting the reasoning budget as discrete steps on a slider. This makes it difficult to set an exact token budget (fine-grained values).

Could you support direct numeric specification of the reasoning budget in addition to the slider?

• Keep the slider for quick adjustment, but also allow entering an exact token count
  • the current token count settings are stored in void-settings.json as .optionsOfModelSelection.Chat.<provider>.<model>.reasoningBudget
• The numeric value should be persisted and respected even if it is not one of the slider's discrete steps