feat(ios): add widget kind option to keep placed widgets across migrations

[rlods]

Summary

Adds an optional kind to iOS widget configs. It overrides the WidgetKit kind of the generated WidgetConfiguration, which today is hardcoded to Voltra_Widget_<id>.

WidgetKit identifies a widget placed on the Home Screen by extension bundle id + kind. targetName already lets an app keep its extension bundle id, but without control over the kind, every widget migrated from a hand-written WidgetKit extension turns into a dead placeholder after the update and users have to remove and re-add it.

With kind pinned to the legacy value, placed widgets pick up the Voltra timeline in place.

[
    '@use-voltra/ios-client', {
        targetName: 'MyWidgets', // existing extension target
        widgets: [
            {
                id: 'streak',
                kind: 'StreakWidget', // to override `Voltra_Widget_<id>`
                displayName: 'Streak',
                description: { … }
            }
        ],
    }
]

Changes

• IOSWidgetConfig.kind?: string, default unchanged (Voltra_Widget_<id>). widgetKind() / widgetKindOverrides() helpers in constants.ts.
• Swift template uses widgetKind(widget) for both StaticConfiguration and AppIntentConfiguration.
• Overrides are written to both Info.plists as Voltra_WidgetKinds: { id: kind } (main app via configureInfoPlist, extension via configureWidgetExtensionPlist).
• New ios/shared/VoltraWidgetKind.swift maps id → kind (plist override, else prefix) and kind → id (reverse lookup, else strip prefix, else nil for non-Voltra kinds). Used by reloadTimeline, getActiveWidgets (so name still reports the widget id), getInstalledWidgetIds (orphan cleanup) and VoltraRefreshIntent. It lives in ios/shared so both podspecs compile it into the app and the extension.
• Validation: kind must be a non-empty string; kinds must be unique across widgets, including a custom kind colliding with another widget's default.
• Docs: kind in the widgets option list plus a "Keeping the kind of an existing widget" section. Changeset: @use-voltra/ios-client minor.

Testing

• pnpm run test in packages/ios-client: 88 tests pass, including new cases for the template (kind used, no Voltra_Widget_ left) and validation (empty kind, duplicate kinds, custom vs default collision).
• pnpm run typecheck, pnpm run lint, swiftformat --lint ios, swift test (69 tests) pass.
• Extension sources plus VoltraWidgetService.swift type-check against the iOS 17 simulator SDK.
• Dogfooding: we run this as a patch on @use-voltra/ios-client@2.2.0 to migrate a production widget from a hand-written WidgetKit extension. On-device upgrade verification is still in progress, hence the draft.

Checklist

• Tests pass (npm test)
• Linting passes (npm run lint:libOnly)
• Formatting is correct (npm run format:check)

🤖 Generated with Claude Code

[rlods]

cc @V3RON 👋 random ping amongst recent contributors, could you please have a look and release if good for you?

[V3RON]

Hey @rlods!

I pushed some commits to make sure your changes are reflected in both the Expo Config Plugin and RN CLI (voltra apply) paths. Let me know if they work for you. If so, I'll merge the PR and release it 👌

[rlods]

I pushed some commits to make sure your changes are reflected in both the Expo Config Plugin and RN CLI (voltra apply) paths. Let me know if they work for you. If so, I'll merge the PR and release it 👌

thanks @V3RON - they look good to me