Migrate preferences from writable stores to runes

[msmolens]

No description provided.

[Copilot]

Pull Request Overview

This PR migrates preferences from Svelte writable stores to runes, modernizing the state management approach. The migration changes how preferences are created, accessed, and managed throughout the codebase.

• Replaced PreferencesManager.createStore() with createPreference() that returns getter functions
• Updated all preference access from $store syntax to function calls like preference()
• Migrated subscription-based reactivity to $effect() for handling preference changes

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/treetop/Treetop.svelte	Updated preference access syntax and replaced store subscription with $effect()
src/treetop/PreferencesManager.ts	Replaced writable stores with SvelteMap and getter functions
src/treetop/PreferencesManager.test.ts	Updated tests to use new preference API and function calls
src/treetop/Folder.svelte.test.ts	Changed test setup to use preference getter functions
src/treetop/Bookmark.svelte.test.ts	Modified test mocks to use preference getter pattern
src/treetop/Bookmark.svelte	Updated preference access from store syntax to function calls
_locales/en/messages.json	Added new error message for history manager refresh

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}