Set default settings to mute sound, no animation, and use system theme

**Is your feature request related to a problem? Please describe.**

I always change those options everytime I install Flow Launcher. I'm pretty sure most people do the same because it gets annoying after a while and the default behavior in Powertoys Run, Wox, and Spotlight Search in macOS don't have sounds or animations.

**Describe the solution you'd like**

I'd like the default settings to at least mute sound and follow the system theme. Disable animation would also be a plus. Changing these default settings will prevent distractions whenever typing a program name or query.

**Describe alternatives you've considered**

N/A Flow Launcher is still my go-to since it's considerably faster than Powertoys Run

**Additional context**

Start by locating the default settings for sound, animation, and system theme in the Flow Launcher codebase. Check how those values are initialized for a fresh installation, then verify that a new installation starts muted, without animation, and using the system theme.

Written by the indexing model from the issue text.