feat: add global and per-post timezone support (#491)

* refactor: replace embedded svg with svg icon

* feat: add global and per-post timezone support

- add `SITE.timezone` in config to define a global default timezone.
- allow per-post timezone overrides via `timezone` in frontmatter.
- update date formatting logic to use the correct timezone when rendering timestamps.
- ensure that posts without a timezone fallback to `SITE.timezone`.
- improve consistency between local and deployed timezones.

* refactor: replace `LOCALE` constant with  `SITE.lang`

* docs: update guides

* fix: update code word-break inside markdown table

Closes #466

src/data/blog/how-to-add-latex-equations-in-blog-posts.md

@@ -1,7 +1,7 @@
 ---
 author: Alberto Perdomo
 pubDatetime: 2024-09-08T20:58:52.737Z
-modDatetime: 2025-03-09T09:24:07.841Z
+modDatetime: 2025-03-22T09:25:46.734Z
 title: How to add LaTeX Equations in Astro blog posts
 tags:
   - docs
@@ -62,7 +62,7 @@ In this section, you will find instructions on how to add support for LaTeX in y
 
    ```astro
    ---
-   import { LOCALE, SITE } from "@config";
+   import { SITE } from "@config";
 
    // astro code
    ---