Add persistent output locale override setting

[Trenly]

📖 Description

Add a persistent output.locale user setting that allows overriding WinGet interface language via a BCP47 tag.

This PR also ensures the override affects MRT resource resolution by setting both ApplicationLanguages::PrimaryLanguageOverride and the global Language qualifier, and updates packaging so local builds can include localized winget.resw files from Localization\Resources\<locale> when Shared\Strings\<locale> is absent.

🔗 References

Resolves #422

🔍 Validation

• Built locally and confirmed settings are read and locale override is applied at startup.
• No additional automated tests were run in-agent.

✅ Checklist

• Signed the Contributor License Agreement
• Linked to an issue
• Updated Release Notes (if applicable)
• Updated documentation (if applicable)
• Updated Copilot instructions (if build, architecture, or conventions changed)

📋 Issue Type

• Bug fix
• Feature
• Task

Microsoft Reviewers: Open in CodeFlow

[florelis]

LGTM, but I'd want to hold off on merging until we have a plan for what to do with App Installer.

[florelis]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[Trenly]

@florelis - I get the same E2E test failures from my last checkout on master

• Edit: Related to Fix portable tests impacted by ADO image #6354

Recording.2026-07-01.224731.mp4

[Copilot]

Pull request overview

Adds a new persisted output.locale user setting that lets WinGet override the UI/output language (via a supported BCP47 tag), and wires the setting into startup initialization so localized resources resolve accordingly. It also updates schema/docs/release notes and adjusts packaging to pick up localized winget.resw files during local builds.

Changes:

• Introduces Setting::OutputLocale (settings mapping + validation/normalization against supported locale tags).
• Applies the locale override at CLI startup via ApplicationLanguages::PrimaryLanguageOverride.
• Updates the settings schema + documentation + release notes, and adds packaging fallback to include localized winget.resw from Localization\Resources\<locale> when Shared\Strings\<locale> is absent.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/AppInstallerCommonCore/UserSettings.cpp	Adds supported-locale normalization and validation for the new output.locale setting.
src/AppInstallerCommonCore/Public/winget/UserSettings.h	Adds the OutputLocale setting enum value and JSON mapping to .output.locale.
src/AppInstallerCLITests/UserSettings.cpp	Adds unit tests covering default/valid/case-insensitive/invalid locale values.
src/AppInstallerCLIPackage/AppInstallerCLIPackage.wapproj	Adds build-time fallback PRIResource includes from Localization\\Resources\\<locale> for local builds.
src/AppInstallerCLICore/Core.cpp	Applies the persisted output locale override during startup initialization.
schemas/JSON/settings/settings.schema.0.2.json	Adds output.locale to the public settings schema with supported enum values.
doc/windows/package-manager/winget/settings.md	Documents the new output.locale setting for end users.
doc/Settings.md	Documents the new output.locale setting in the repo’s settings documentation.
doc/ReleaseNotes.md	Adds a release note entry for the new output locale override feature.

[florelis]

/azp run

[azure-pipelines]

Azure Pipelines:
Successfully started running 1 pipeline(s).

[florelis]

Looks like we will need to reset the override in App Installer. Internal PR number for that: 16173490
I won't merge this until that other change is in place.

[florelis]

Question from internal discussion:
Instead of overriding the primary language like this, would it be possible to just add the locale qualifier when creating the resource loader? That would avoid setting the locale package-wide, and we wouldn't need to make any changes to App Installer.