Localize Debug Settings comments (PT-BR) with English fallback

[vedned]

Description

The Debug Settings panel (Advanced → Show Debug Settings) shows a help comment for each setting. Until now these comments were always displayed in English, regardless of the language selected in the viewer, because they are read directly from app_settings/settings.xml at runtime. This made advanced configuration harder for non-English speakers.

This PR introduces localized Debug Settings comments: when a translation file exists for the active language, the viewer displays the setting descriptions in that language. When it does not, the previous behavior (English) is fully preserved. It also ships a complete PT-BR translation as the first implementation.

What changes

After the session language is initialized, the viewer loads skins/default/xui/{locale}/settings_comments.xml and overrides the comments of the existing controls at runtime, for both the Global and PerAccount settings groups.

Implementation

• Added LLAppViewer::loadLocalizedSettingsComments() and a helper apply_localized_comments() in indra/newview/llappviewer.cpp.
• Declared the new method in indra/newview/llappviewer.h.
• The call is placed right after the skin/language is set, so LLUI::getLanguage() is already valid and the default English comments have already been loaded.
• The localized file is located with gDirUtilp->findSkinnedFilename(LLDir::XUI, "settings_comments.xml", LLDir::CURRENT_SKIN), which returns the most-localized existing path, or an empty string when none exists.
• The file is parsed with LLSDSerialize::fromXML into a simple LLSD map (SettingName -> "translated comment"), and each entry overrides the comment of the matching control via LLControlVariable::setComment().

Why it is safe

• getControl() returns an LLControlVariablePtr (smart pointer); the helper checks notNull() before writing.
• Controls and default English comments are loaded earlier in initConfiguration() via loadSettingsFromDirectory("Default", set_defaults=true), before this call.
• The post-login account settings load uses set_defaults=false, which does not call setComment(), so translated comments are not overwritten later.
• No new includes were required (llsdserialize.h and llviewercontrol.h already included).

Fallback behavior

1. No file for the locale → the whole language keeps the English comments.
2. Missing key inside the file → that specific setting keeps its English comment.

PT-BR content

• Added indra/newview/skins/default/xui/pt/settings_comments.xml covering 1,507 settings (1,466 from settings.xml + 41 from settings_per_account.xml), validated as well-formed XML, with consistent terminology across families of settings.
• Completed the missing labels in indra/newview/skins/default/xui/pt/floater_settings_debug.xml.

Files changed

• indra/newview/llappviewer.h
• indra/newview/llappviewer.cpp
• indra/newview/skins/default/xui/pt/settings_comments.xml (new)
• indra/newview/skins/default/xui/pt/floater_settings_debug.xml

Related Issues

Issue Link: relates to #5955

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Checklist

• I have provided a clear title and detailed description for this pull request.
• If useful, I have included media such as screenshots and video to show off my changes.
• The PR is linked to a relevant issue with sufficient context.
• I have tested the changes locally and verified they work as intended.
• All new and existing tests pass.
• Code follows the project's style guidelines.
• Documentation has been updated if needed.
• Any dependent changes have been merged and published in downstream modules
• I have reviewed the contributing guidelines.

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Additional Notes

Debug Settings Português:

2026-06-25.16-05-15.mp4

How to test

1. Build and run the viewer.
2. Set the language to Português (Brasil) and restart if prompted.
3. Enable the Advanced menu in Preferences → Advanced → "Show Advanced Menu".
4. Open Advanced → Show Debug Settings.
5. Select several settings and confirm the help comments are shown in Portuguese.
6. Switch to a language without a settings_comments.xml and confirm comments fall back to English.
7. Confirm a setting key not present in the PT file still shows its English comment.

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[vedned]

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