feat: sort languages in selection menu (#1071)

## Summary

* **What is the goal of this PR?** (e.g., Implements the new feature for
file uploading.)

Currently we are displaying the languages in the order they were added
(as in the `Language` enum). However, as new languages are coming in,
this will quickly be confusing to the users.

But we can't just change the ordering of the enum if we want to respect
bakwards compatibility.

So my proposal is to add a mapping of the alphabetical order of the
languages. I've made it so that it's generated by the `gen_i18n.py`
script, which will be used when a new language is added.


* **What changes are included?**

Added the array from the python script and changed
`LanguageSelectActivity` to use the indices from there. Also commited
the generated `I18nKeys.h`

## Additional Context

* Add any other information that might be helpful for the reviewer
(e.g., performance implications, potential risks,
  specific areas to focus on).

I was wondering if there is a better way to sort it. Currently, it's by
unicode value and Czech and Russian are last, which I don't know it it's
the most intuitive.

The current order is:
`Català, Deutsch, English, Español, Français, Português (Brasil),
Română, Svenska, Čeština, Русский`

---

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docs/i18n.md

@@ -52,7 +52,7 @@ A file looks like this:
 
 ```yaml
 _language_name: "Español"
-_language_code: "SPANISH"
+_language_code: "ES"
 _order: "1"
 
 STR_CROSSPOINT: "CrossPoint"
@@ -62,7 +62,7 @@ STR_BROWSE_FILES: "Buscar archivos"
 
 **Metadata keys** (prefixed with `_`):
 - `_language_name` — Native display name shown to the user (e.g. "Français")
-- `_language_code` — C++ enum name (e.g. "FRENCH"). Must be a valid C++ identifier.
+- `_language_code` — C++ enum name (e.g. "FR"). Please use the [ISO Code](https://en.wikipedia.org/wiki/List_of_ISO_639_language_codes) of the language. Must be a valid C++ identifier.
 - `_order` — Controls the position in the Language enum (English is always 0)
 
 **Rules:**
@@ -128,7 +128,7 @@ Create `lib/I18n/translations/italian.yaml`:
 
 ```yaml
 _language_name: "Italiano"
-_language_code: "ITALIAN"
+_language_code: "IT"
 _order: "7"
 
 STR_CROSSPOINT: "CrossPoint"
@@ -175,7 +175,7 @@ renderer.drawText(font, x, y, tr(STR_BROWSE_FILES));
 Serial.printf("Status: %s\n", tr(STR_CONNECTED));
 
 // I18N - Shorthand for I18n::getInstance()
-I18N.setLanguage(Language::SPANISH);
+I18N.setLanguage(Language::ES);
 Language lang = I18N.getLanguage();
 
 // === Full API ===
@@ -189,7 +189,7 @@ const char* text = I18N.get(StrId::STR_SETTINGS_TITLE);   // Direct call
 const char* text = I18N[StrId::STR_SETTINGS_TITLE];       // Operator overload
 
 // Set language
-I18N.setLanguage(Language::SPANISH);
+I18N.setLanguage(Language::ES);
 
 // Get current language
 Language lang = I18N.getLanguage();
@@ -201,7 +201,7 @@ I18N.saveSettings();
 I18N.loadSettings();
 
 // Get character set for font subsetting (static method)
-const char* chars = I18n::getCharacterSet(Language::FRENCH);
+const char* chars = I18n::getCharacterSet(Language::FR);
 ```
 
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