i18n: add Brazilian Portuguese (pt-br) UI translation (#165)

* M14: translation catalogs, same system as PhotoCraft

Move the interface translations to PhotoCraft's i18n system: one TSV
catalog per language (crates/ui-egui/src/i18n/ja.tsv), the tl! macro,
entries keyed by command id, context or plural forms, and catalog tests
(format, duplicates, placeholders, command ids).

The 49 existing Japanese strings move over unchanged, plus "Auto". The
language preference now defaults to "auto" and follows the system
language (English when it has no catalog); "en" and "ja" still persist
and unknown values are rejected.

Update docs/localization.md, ROADMAP.md and the misc.prefs-language
parity entry.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

* i18n: add Brazilian Portuguese (pt-br) UI translation

Adds Language::PtBr (code pt-br, endonym Português (Brasil)) with serde rename so it persists as "pt-br", registers it in Language::ALL (Preferences ▸ Interface language and ui.set/ui.state) and translates the same 49 menu/command keys as the Japanese table. Extends the i18n tests (table parity, codes, persistence) and updates docs/localization.md.

* M14: strict catalog validation, one-pass fmt, translation assets

Fold in the infrastructure parts of #175:
- `fmt` fills placeholders in one pass, so inserted values (a file name
  containing `{n}`) are never substituted again.
- Catalog validation rejects unknown escapes, unknown `@` contexts,
  placeholder, ellipsis and plural-form mismatches and duplicates. The
  bundled catalogs must have no errors (tests); at run time a bad line is
  still only skipped and logged, so the rest of the catalog loads.
- `.tsv` files count as assets in `cargo xtask assets`, with a
  `translation` kind that may never come from Adobe; ja.tsv gets its
  ATTRIBUTION.toml entry.
- Control-channel test: switching the language keeps documents, their
  dirty state and command ids.

Also make the drawing language thread-local, as in PhotoCraft, so
parallel kittest harnesses can't change each other's language.

Co-Authored-By: 才倾梦华V <[email protected]>
Co-Authored-By: Claude Opus 5.5 <[email protected]>

* M14: Brazilian Portuguese as a TSV catalog

Move #165's Portuguese table into crates/ui-egui/src/i18n/pt-br.tsv
(same 49 strings, plus Auto) and register it in LANGUAGES with
PhotoCraft's Portuguese plural rule (0 and 1 singular). Any Portuguese
locale (pt_BR, pt_PT, pt) follows the Brazilian catalog, as in
PhotoCraft. The catalog is an attributed asset (ATTRIBUTION.toml), and
the docs and parity notes list the new code.

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

---------

Co-authored-by: Simon Leblanc <[email protected]>
Co-authored-by: Claude Opus 5.5 (1M context) <[email protected]>
Co-authored-by: Brandon Thomas <[email protected]>
Co-authored-by: 才倾梦华V <[email protected]>

docs/localization.md

@@ -1,8 +1,8 @@
 # Interface language
 
-Choose **Edit > Preferences > Interface language** and select **Auto**, **English** or **日本語**. The change applies immediately and persists between launches. Command ids, document contents and file names are unchanged.
+Choose **Edit > Preferences > Interface language** and select **Auto**, **English**, **日本語** or **Português (Brasil)**. The change applies immediately and persists between launches. Command ids, document contents and file names are unchanged.
 
-**Auto** (the default) follows the system language: `LC_ALL`, `LC_MESSAGES` or `LANG`, then the preferred-languages list on macOS. A system language without a catalog, such as French, shows English. Windows has no system-language detection yet, so **Auto** shows English there unless `LANG` is set.
+**Auto** (the default) follows the system language: `LC_ALL`, `LC_MESSAGES` or `LANG`, then the preferred-languages list on macOS. Any Portuguese locale (`pt_BR`, `pt_PT`) uses the Brazilian catalog. A system language without a catalog, such as French, shows English. Windows has no system-language detection yet, so **Auto** shows English there unless `LANG` is set.
 
 The control channel exposes the setting through `ui.set`:
 
@@ -10,11 +10,11 @@ The control channel exposes the setting through `ui.set`:
 {"method":"ui.set","params":{"key":"language","value":"ja"}}
 ```
 
-The value is `auto` or a language code (`en`, `ja`), in any case. `ui.state` reports `language` as written in the preferences (`auto`, `en` or `ja`). Unknown values return an error without changing the current setting. Preferences saved before this setting existed follow the system language.
+The value is `auto` or a language code (`en`, `ja`, `pt-br`), in any case. `ui.state` reports `language` as written in the preferences (`auto`, `en`, `ja` or `pt-br`). Unknown values return an error without changing the current setting. Preferences saved before this setting existed follow the system language.
 
 This first translation pass covers the main menu and core registered menu commands. Untranslated labels use English. Vertical Japanese PDF rendering is an existing viewer feature; this change does not add vertical text editing.
 
-Japanese interface text uses BIZ UDPGothic from [craft-fonts](https://github.com/storytold/craft-fonts), an optional build input that every release includes (`CRAFT_FONTS_DIR`; see the README). A build made without it has no Japanese face, so Japanese labels show replacement boxes.
+Japanese interface text uses BIZ UDPGothic from [craft-fonts](https://github.com/storytold/craft-fonts), an optional build input that every release includes (`CRAFT_FONTS_DIR`; see the README). A build made without it has no Japanese face, so Japanese labels show replacement boxes. Brazilian Portuguese needs only the bundled Latin faces.
 
 ## How translations work