fix: Apply default value to slider

[rht]

Without this, the slider value always defaults to being leftmost.

[github-actions]

Performance benchmarks:

Model	Size	Init time [95% CI]	Run time [95% CI]
Schelling	small	🔵 +0.0% [-0.3%, +0.4%]	🔵 +0.1% [-0.2%, +0.4%]
Schelling	large	🔵 +0.1% [-1.2%, +1.1%]	🔵 -1.0% [-2.4%, +0.7%]
WolfSheep	small	🔵 -0.0% [-0.3%, +0.3%]	🔵 -0.1% [-0.2%, +0.0%]
WolfSheep	large	🔵 +0.7% [-0.1%, +1.5%]	🔵 +1.2% [+0.1%, +2.5%]
BoidFlockers	small	🔵 -0.4% [-0.8%, -0.0%]	🔵 -0.7% [-1.2%, -0.1%]
BoidFlockers	large	🔵 -0.2% [-0.5%, +0.0%]	🔵 -0.5% [-1.0%, -0.0%]