feat: introduce Expressive Code for code block rendering (#476)

* feat: improve code block feature with Expressive Code

* docs: add example Markdown file for visual review

* feat: improve styles of Expressive Code

* fix: errors from the merging

* chore: formatting

* chore: update config

* chore: update dependencies

* fix: fix build error

* fix: minor fixes

* fix: style tweaks

* docs: update example post

* fix: isolate copy button timeouts to avoid cross-button interference

---------

Co-authored-by: Hasenpfote <Hasenpfote36@gmail.com>

src/types/config.ts

@@ -86,3 +86,7 @@ export type BlogPostData = {
 	nextTitle?: string;
 	nextSlug?: string;
 };
+
+export type ExpressiveCodeConfig = {
+	theme: string;
+};