🌐 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/macros/set_title.html

@@ -1,4 +1,4 @@
-{%- macro set_title() -%}
+{%- macro set_title(language_strings="") -%}
 
 {# Setup. #}
 {%- set prefix = config.title | safe -%}
@@ -26,7 +26,7 @@
     {%- set suffix = term.name -%}
 {% elif taxonomy.name %}
     {# List of tags. #}
-    {%- set suffix = macros_translate::translate(key=taxonomy.name) | capitalize -%}
+    {%- set suffix = macros_translate::translate(key=taxonomy.name, language_strings=language_strings) | capitalize -%}
 {% else %}
     {%- set suffix = "404" %}
 {%- endif -%}