feat: add theme management with light and dark modes

- Implemented a new composable `useTheme` for managing theme state.
- Added functions to read and write theme preference to local storage.
- Applied theme styles to the DOM based on user preference.
- Introduced a toggle function to switch between light and dark themes.

refactor: enhance copilot plugin functionality

- Improved request handling with sequence and document versioning.
- Refactored ghost text handling to improve clarity and efficiency.
- Updated markdown insertion logic to handle parsed content more robustly.
- Enhanced error handling and logging for better debugging.

style: update global styles for light and dark themes

- Defined CSS variables for light and dark themes to streamline styling.
- Improved overall styling consistency and responsiveness.
- Added transitions for smoother theme changes and interactions.

.build-check/assets/vendor-mdast-util-definitions-CBjSIrGZ.js

@@ -0,0 +1 @@
+import{v as c}from"./vendor-unist-util-visit-8PRsQcuP.js";function s(n){const e=new Map;if(!n||!n.type)throw new Error("mdast-util-definitions expected node");return c(n,"definition",function(t){const i=o(t.identifier);i&&!e.get(i)&&e.set(i,t)}),r;function r(t){const i=o(t);return e.get(i)}}function o(n){return String(n||"").toUpperCase()}export{s as d};