* 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