feat: card locale translations (#509)

* Add Card Translations

* Add tests and documentation for `?lang` option

* Card Translations: update Italian

* Run Prettier

* Correct German Translations.

Co-authored-by: schmelto <30869493+schmelto@users.noreply.github.com>

* refactor: added i18n class to manage translation logic & improved code

* Make the new src/translations.js more concise

* Update translations.js

Co-authored-by: schmelto <30869493+schmelto@users.noreply.github.com>

* Revert 4175484d69289e4ee7283ab968b8e71c3c5d77df

* fix: overlap because of language length

Co-authored-by: lrusso96 <russo.1699981@studenti.uniroma1.it>
Co-authored-by: schmelto <30869493+schmelto@users.noreply.github.com>
Co-authored-by: Anurag <hazru.anurag@gmail.com>

api/index.js

@@ -5,6 +5,7 @@ const {
   parseArray,
   clampValue,
   CONSTANTS,
+  isLocaleAvailable,
 } = require("../src/common/utils");
 const fetchStats = require("../src/fetchers/stats-fetcher");
 const renderStatsCard = require("../src/cards/stats-card");
@@ -28,6 +29,7 @@ module.exports = async (req, res) => {
     theme,
     cache_seconds,
     custom_title,
+    locale,
   } = req.query;
   let stats;
 
@@ -37,6 +39,10 @@ module.exports = async (req, res) => {
     return res.send(renderError("Something went wrong"));
   }
 
+  if (locale && !isLocaleAvailable(locale)) {
+    return res.send(renderError("Something went wrong", "Language not found"));
+  }
+
   try {
     stats = await fetchStats(
       username,
@@ -67,6 +73,7 @@ module.exports = async (req, res) => {
         bg_color,
         theme,
         custom_title,
+        locale: locale ? locale.toLowerCase() : null,
       }),
     );
   } catch (err) {