Task: Migrate Legacy Svelte Stores to Runes

# Task: Migrate Svelte Stores to Runes

## Description  

There have been some functionality issues observed while implementing current Svelte related issues regarding the legacy Svelte `$store` usage due to Svelte 5 introducing Runes as a replacement.

This task is for migrating _all_ of the legacy stores to utilize the rune development structure.

It had previously been determined that if a developer was working an issue that "touched" a svelte file then they should go ahead and perform the required migration. This is no longer a viable solution due to the numerous derived stores that currently exist. Legacy stores written as `$derived` do not perform well when the variable's dependent derivation has been changed to a Svelte 5 rune.

## Acceptance Criteria  

- No legacy svelte stores in use.
- Functionality remains in tact.

### Steps / Subtasks

Ideally, the `index.ts` file that contains the UI global svelte stores should be worked first.

Note: If we go with the standalone Data Editor as described in https://github.com/ctc-oss/omega-edit/discussions/1481 . This issue will not be applicable as standalone Data Editor already does this.