Update to new Stan tooling

What's Changed

• Update core to 2025 by @mhpob in #1
• Move repos by @mhpob in #11
• Switch GHA from build check to full R CMD check by @mhpob in #12
• Reviewed, reformatted, and optimized Stan code by @benjaminhlina in #18
• Add Winton et al. 2018 reference to README and vignette by @mhpob in #17
• Use stats:: for median and quantile by @mhpob in #20
• Re-style vignette by @mhpob in #23
• Update tests by @benjaminhlina in #25

New Contributors

• @mhpob made their first contribution in #1
• @benjaminhlina made their first contribution in #18

Full Changelog: v1.0.0...v1.1.0

first release

v1.0.0

Update vignette.