Arabic (العربية) UI translation: language switching + font fallback (#798)

* Show Thai file names and text in the interface with an installed Thai font

A drawing whose file name is Thai showed boxes in its file tab and in the
window title: the interface loaded one Latin system font (plus a CJK font for
the Chinese interface), and neither has Thai.

install_fonts now also adds an installed Thai font (Thonburi, Leelawadee UI,
Noto Sans Thai, Loma...) after the Latin one, in any interface language, since
file names and drawing text are Thai whatever the interface is in. No font is
bundled; without one installed nothing changes.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

* Add Korean interface localization and Hangul font support

* Add Arabic (العربية) interface translation

A full ar.tsv catalog for the CAD interface — every menu label, tool,
palette, dialog and status message in the repo's three-column TSV
format, written from the plain meaning of the English with the
Arabic AutoCAD vocabulary its users know (أمر، إزاحة، تدوير، قص،
استدارة، طبقة…), with the six CLDR plural forms for the counts.
Registers ar in LANGUAGES with plural_arabic and the font chain
(Noto Sans Arabic first on Linux, Segoe UI/Tahoma on Windows, Geeza
Pro on macOS) so the UI families paint Arabic.

The shell itself still lays out left-to-right: egui 0.36 has no
global direction switch and no bidi, so mirroring is left for a
later pass; this PR is the catalog, the registry entry and the
fonts.

* i18n: start the Swedish (sv) interface catalog

Header only, not registered yet: the catalog is filled and the language registered in this
branch, translated from the meaning of CADCraft's English strings and reviewed by a native
Swedish speaker.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

* i18n: add Swedish (sv) interface translation

A complete 1,235-entry Swedish catalog: every key of the Spanish catalog, Run Script... and the
four menu headings (Visa, Rita, Måttsättning, Ändra). Written from the meaning of CADCraft's
English strings; no other product's localisation and no other catalog was used. AI-assisted; the
terminology and the running app were reviewed by a native speaker. Command-line keywords, system
variables and osnap tokens stay English.

- Preference::Swedish (sv); sv-SE, sv-FI and sv_SE.UTF-8 select it; one|other plurals (the
  English rule).
- sv in REPORTED; tests for locales, saved preference and plurals, menu headings, a live switch,
  dialogs and the Swedish letters in the bundled fonts. No gaps are reported for Swedish.
- ATTRIBUTION, README, docs/localization.md, docs/localization-parity.md,
  docs/control-protocol.md, the options doc comment and a contributors/people.toml entry for
  @holmbom.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

---------

Co-authored-by: Chanthawat Kiriyadee <[email protected]>
Co-authored-by: Claude Opus 5.5 <[email protected]>
Co-authored-by: huk082 <[email protected]>
Co-authored-by: hasan-sdaif <[email protected]>
Co-authored-by: Erik Holmbom <[email protected]>
Co-authored-by: Brandon Thomas <[email protected]>

docs/control-protocol.md

@@ -152,8 +152,8 @@ Select a language with `engine.execute` and the UI command `ui.language`:
 {"id":1,"method":"engine.execute","params":{"command":"ui.language","params":{"lang":"uk"}}}
 ```
 
-Supported values are `auto`, `en`, `uk`, `pt-BR`, `de`, `es`, `cs`, `ru`, `fr`, `zh`, `it`, `ko` and `sv`.
-Chinese needs an installed CJK font; Korean needs a font covering the Korean interface from the
+Supported values are `auto`, `en`, `uk`, `pt-BR`, `de`, `es`, `cs`, `ru`, `fr`, `zh`, `it`, `ko`, `sv` and `ar`.
+Chinese needs an installed CJK font, Arabic an installed Arabic font; Korean needs a font covering the Korean interface from the
 optional craft-fonts input or the operating system. Without a suitable font, the saved choice is
 retained and the result's `shown` is `en`. `ui.set` also accepts
 `{"interfaceLanguage":"uk"}`; `ui.inspect` reports the saved choice in its UI state.

docs/localization.md

@@ -1,7 +1,7 @@
 # Interface languages
 
 Choose **Edit → Interface Language** and select **Auto (system language)**, **English**,
-**Українська**, **Português (Brasil)**, **Deutsch**, **Español**, **Čeština** (Czech), **Русский**, **Français**, **简体中文**, **Italiano**, **한국어** (Korean), or **Svenska** (Swedish).
+**Українська**, **Português (Brasil)**, **Deutsch**, **Español**, **Čeština** (Czech), **Русский**, **Français**, **简体中文**, **Italiano**, **한국어** (Korean), **Svenska** (Swedish), or **العربية** (Arabic).
 The interface updates without restarting, including the native macOS menus.
 The choice is saved with the other interface preferences (`cadcraft.prefs`, beside the theme):
 eframe storage on the desktop, browser local storage on the web. Installations without a saved
@@ -22,7 +22,7 @@ Automation can select the language through the existing control channel:
 ```
 
 The `ui.set` method also accepts `{"interfaceLanguage":"cs"}`. Supported values are `auto`,
-`en`, `uk`, `pt-BR`, `de`, `es`, `cs`, `ru`, `fr`, `zh`, `it`, `ko`, and `sv`; invalid values are rejected without changing the current
+`en`, `uk`, `pt-BR`, `de`, `es`, `cs`, `ru`, `fr`, `zh`, `it`, `ko`, `sv`, and `ar`; invalid values are rejected without changing the current
 selection. Resetting palettes keeps the language choice.
 
 ## Translation coverage