fix: Svelte runes detection not working correctly in monorepos

[hmnd]

Description

347 introduced support for Svelte 5 runes. In doing so, the Svelte plugin now imports from svelte/compiler. Without svelte being listed as an optional peer dependency, the import did not correctly resolve svelte from the current workspace within a monorepo. Thus, if another package in the monorepo depended on Svelte 5, a package depending on Svelte 4 could be misidentified as the newer version.

[stackblitz[bot]]

Run & review this pull request in StackBlitz Codeflow.

[userquin]

/cc @benmccann @dominikg

[userquin]

@hmnd @benmccann to release this we also need this another PR #381 and switch types/svelte to types/svelte5 adding the corresponding subpacka exports.