i18n(fa): add Persian interface translation (#4558)

* i18n(fa): add Persian interface translation catalog

Add crates/ui-egui/src/i18n/fa.tsv covering the current 2,776-key union, register fa (right-to-left, one/other plurals) in i18n and the date languages, and credit the catalog in ATTRIBUTION.

* i18n(fa): fix missing ZWNJ in compound suffixes

Join participles (شده/نشده) and productive suffixes (سازی, گذاری, گیری, بندی, پذیری, کننده, ...) and compound prefixes (هم, غیر, پیش, پس, چند, تک, باز) with U+200C, plus reviewer wording fixes.

* fix(i18n): Persian counts 0 as singular (CLDR fa) and writes weekday names with ZWNJ

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Brandon Thomas <echelon@gmail.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

crates/engine/src/dates.rs

@@ -63,7 +63,7 @@ const CKB_DAYS: [&str; 7] = ["یەکشەممە", "دووشەممە", "سێشەم
 
 /// The languages month and weekday names can be written in (Preferences ▸ Date format ▸ Language):
 /// the interface languages, in the same order and with the same names.
-pub static DATE_LANGUAGES: [DateLanguage; 34] = [
+pub static DATE_LANGUAGES: [DateLanguage; 35] = [
     DateLanguage {
         code: "en",
         name: "English",
@@ -267,6 +267,17 @@ pub static DATE_LANGUAGES: [DateLanguage; 34] = [
         days: CKB_DAYS,
         days_short: CKB_DAYS,
     },
+    // Persian (Farsi); Gregorian month and weekday names, right to left like Arabic and Kurdish.
+    // Persian does not change the month form after a day number, so `months_with_day` is `None`.
+    DateLanguage {
+        code: "fa",
+        name: "فارسی",
+        months: ["ژانویه", "فوریه", "مارس", "آوریل", "مه", "ژوئن", "ژوئیه", "اوت", "سپتامبر", "اکتبر", "نوامبر", "دسامبر"],
+        months_with_day: None,
+        months_short: ["ژانویه", "فوریه", "مارس", "آوریل", "مه", "ژوئن", "ژوئیه", "اوت", "سپتامبر", "اکتبر", "نوامبر", "دسامبر"],
+        days: ["یکشنبه", "دوشنبه", "سه‌شنبه", "چهارشنبه", "پنج‌شنبه", "جمعه", "شنبه"],
+        days_short: ["یک", "دو", "سه", "چه", "پن", "جم", "شن"],
+    },
     DateLanguage {
         code: "pl",
         name: "Polski",