FR: Swap grid implementation from Canvas to a background SVG

## [From Discord](https://discord.com/channels/1218270712402415686/1247306607709393017/1410415464349171716)

> Canvas grid is one thing that could do with a tweak.. currently it's using a bitmap that scales and pans with the canvas. Using a background image (svg) with non-scaling line widths on the html instead, with size set to cover keeps the grid fixed in the viewport, which arguably is better behavior.. doesn't need to be handled at the canvas level, potentially improving viewport responsiveness, and a non-scaling fixed-line-width svg is much cleaner.

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-5243-FR-Swap-grid-implementation-from-Canvas-to-a-background-SVG-25d6d73d365081a0bbbceb3c6e44dd53) by [Unito](https://www.unito.io)