🌐 feat(i18n): overhaul translation system & add languages (#145)

Revamp the existing translation system, simplifying
management and adding several new languages. The new system reads from
TOML files in the `/i18n` directory and improves template structures.
It also enhances customisation options and robustness by providing
fallbacks and modularity.

- Implement a new, streamlined translation macro.
- Load translations from `/i18n` TOML files.
- Remove redundant configuration requirements.
- Refactor templates to align with new i18n system.
- Add support for Hindi, Japanese, Russian, Portuguese, Chinese,
  Italian, German, Ukranian, Korean, and French languages.
- Credit Thomas Weitzel (@thomasweitzel) for inspiration.

templates/partials/header.html

@@ -4,7 +4,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
 
     {# Site title #}
-    <title>{{ macros_set_title::set_title() }}</title>
+    <title>{{ macros_set_title::set_title(language_strings=language_strings) }}</title>
 
     {# Favicon #}
     {% if config.extra.favicon %}