v0.8.18

## What's Changed
* doc(`leptos_config`): Improve docs readability; Add `# Errors` sections by @DanikVitek in https://github.com/leptos-rs/leptos/pull/4593
* feat(`leptos_config`): Implement `LeptosOptions::css_path` by @DanikVitek in https://github.com/leptos-rs/leptos/pull/4592
* fix: prevent circular reference in `Action` by using `WeakOwner` (closes #4602) by @gbj in https://github.com/leptos-rs/leptos/pull/4603
* Better implementation of `css_path` with that moved to `css_file_path` to better reflect/compliment underlying use cases by @metatoaster in https://github.com/leptos-rs/leptos/pull/4615
* feat: Extend either macro by @domwst in https://github.com/leptos-rs/leptos/pull/4613
* Update readme playground link to that of leptos.dev by @xiaogz in https://github.com/leptos-rs/leptos/pull/4625
* chore: update nightly toolchain and adjust trybuild stderr by @gbj in https://github.com/leptos-rs/leptos/pull/4626
* chore: actually test nightly in CI by @gbj in https://github.com/leptos-rs/leptos/pull/4637
* Fixes deriving `Patch` for `Store` where `store` attribute is being used. by @mskorkowski in https://github.com/leptos-rs/leptos/pull/4620
* Document getrandom/rand setup for wasm32 builds, closes #3979 by @ordokr in https://github.com/leptos-rs/leptos/pull/4648
* A few `Store` cleanup items by @gbj in https://github.com/leptos-rs/leptos/pull/4645
* Fix typo: occured -> occurred in leptos_config doc comment in https://github.com/leptos-rs/leptos/pull/4657
* fix: don't panic on invalid UTF-8 in paths (closes #4662) by @gbj in https://github.com/leptos-rs/leptos/pull/4663
* Deriving Store no longer generates warning about missing docs by @mskorkowski in https://github.com/leptos-rs/leptos/pull/4671
* chore(deps): bump pnpm/action-setup from 4 to 5 by @dependabot[bot] in https://github.com/leptos-rs/leptos/pull/4658
* feat(`either_of`): Add `Either!` convenience macro by @DanikVitek in https://github.com/leptos-rs/leptos/pull/4627
* chore: pull in latest `wasm_split_helpers` version by @gbj in https://github.com/leptos-rs/leptos/pull/4684

## New Contributors
* @xiaogz made their first contribution in https://github.com/leptos-rs/leptos/pull/4625
* @ordokr made their first contribution in https://github.com/leptos-rs/leptos/pull/4648

**Full Changelog**: https://github.com/leptos-rs/leptos/compare/v0.8.17...v0.8.18