Runes migration

[mitchthorson]

What's in this pull request

• Other

Description

This pull request contains a library-wide refactor toward Svelte 5 runes syntax across all Svelte components and documentation. Functionality is left unchanged, except where bugs or inconsistencies were fixed as part of this migration. This should behave just as the library did before, with just a few breaking changes related to moving away from Svelte Stores for shared state.

Note that generative AI tools were used to assist with this refactor, including Anthropic's Claude Code CLI and Open AI's Codex CLI. Every change has been manually reviewed and verified by a human developer through multiple rounds of careful review.

Before submitting, please check that you've

• Formatted your code correctly (i.e., prettier cleaned it up)
• Documented any new components or features
• Added any changes in this PR to the CHANGELOG.md Next section
• If this pull request includes a new component or feature, has it been exported from one of the library's entry points?
• Does the component directory include description and usage information in .stories.svelte?

[mitchthorson]

I've re-reviewed each of these changes and made a few slight adjustments.

[rachelmarconi]

truly last thing and feel free to ignore -- in almost all cases (except SvgPointLayer, SvgPolygonLayer and SvgLabelLayer), the controls panel has bulleted descriptions in the second column above the types. I'm trying to track down what changed since this is new but oddly inconsistent -- it's not like the maps subfolder has a different controls or autodocs template.

[mitchthorson]

Ok, all of these review notes have been resolved. Thank you for your time and energy on this @rachelmarconi. Going to rebase and merge.