feat(iOS, Stack v5): Refactor Stack Header implementation and handle selective updates

[kmichalikk]

Closes https://github.com/software-mansion/react-native-screens-labs/issues/1567

Description

This PR decouples React component views from native UIKit logic and introduces selective item updates so only the changed item rebuilds.

Changes

• removed menu state tracker from ComponentView
• removed RNSStackHeaderData data class, now props are read directly from ComponentView via protocol
• merged RNSStackHeaderItemCoordinator into RNSStackHeaderCoordinator and removed the class
• added selective rebuilds with itemId
• split menu rebuild from item rebuild; if only menu changes, item doesn't get rebuilt
• when menu or item definition changes, the state for menu is cleared and reset to defaults - this is by design to match android
• added SFT for visually inspecting the updates
• unfortunately, I was unable to make the coordinator stateless because it needs to hold references to header items and state trackers for rebuilding (bar items in UIKit are immutable)

Before & after - visual documentation

Before	After
no-selective-updates.mov	selective-updates.mov

Test plan

Use test-stack-header-selective-updates-ios.

Checklist

• Included code example that can be used to test this change.
• For visual changes, included screenshots / GIFs / recordings documenting the change.
• For API changes, updated relevant public types.
• Ensured that CI passes

[kmichalikk]

the protocol defines because I don't want to leak react views here & only need to handle 2 data providing protocols for items and spacers

[Copilot]

Pull request overview

This PR refactors the iOS (gamma / Stack v5) header implementation to decouple native UIKit updates from React component views, and introduces selective updates so only the affected header item (or only its menu) is rebuilt.

Changes:

• Replaces the previous “build RNSStackHeaderData then apply” flow with a coordinator that reads config + children directly via RNSStackHeaderConfigDataProviding.
• Adds selective update entry points (rebuildItemWithId, reapplyMenuForItemWithId) and a menu tracker registry to preserve menu toggle state across interactions.
• Adds a new Single Feature Test scenario for visually validating selective updates on iOS.

Reviewed changes

Copilot reviewed 27 out of 27 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
ios/gamma/stack/screen/RNSStackScreenHeaderCoordinator.mm	New coordinator-driven rebuild + selective item/menu update logic; new menu tracker registry integration.
ios/gamma/stack/screen/RNSStackScreenHeaderCoordinator.h	Exposes coordinator API and provider/delegate wiring (config, frame changes, events).
ios/gamma/stack/screen/RNSStackScreenComponentView.h	Removes dependency on RNSStackHeaderData.
ios/gamma/stack/screen/RNSStackNavigationItemCoordinator.mm	Deleted (logic moved into header coordinator).
ios/gamma/stack/screen/RNSStackNavigationItemCoordinator.h	Deleted (logic moved into header coordinator).
ios/gamma/stack/host/RNSStackNavigationBarCoordinator.mm	Simplifies API to setHidden:animated:.
ios/gamma/stack/host/RNSStackNavigationBarCoordinator.h	Header update for the simplified navigation bar API.
ios/gamma/stack/header/RNSStackHeaderMenuTrackerRegistry.mm	New registry storing per-item toggle state trackers.
ios/gamma/stack/header/RNSStackHeaderMenuTrackerRegistry.h	Header for the new tracker registry.
ios/gamma/stack/header/RNSStackHeaderMenuCoordinator.mm	Adds menuToggleCallback so callers can reapply menus after toggle interactions.
ios/gamma/stack/header/RNSStackHeaderMenuCoordinator.h	Documents and exposes the new menuToggleCallback API.
ios/gamma/stack/header/RNSStackHeaderItemSpacerComponentView.mm	Updates invalidation callback name for spacer changes.
ios/gamma/stack/header/RNSStackHeaderItemInvalidationDelegate.h	Splits invalidation into item rebuild vs menu-only update vs spacer rebuild.
ios/gamma/stack/header/RNSStackHeaderItemDataProviding.h	Removes menu toggle tracker from the item-providing protocol (now coordinator-managed).
ios/gamma/stack/header/RNSStackHeaderItemComponentView.mm	Emits selective invalidations (rebuild item vs menu-only change).
ios/gamma/stack/header/RNSStackHeaderItemComponentView.h	Adds RNSViewFrameChangeDelegate conformance; updates exposed surface.
ios/gamma/stack/header/RNSStackHeaderData.mm	Deleted (no longer used).
ios/gamma/stack/header/RNSStackHeaderData.h	Deleted (no longer used).
ios/gamma/stack/header/RNSStackHeaderContentFactory.mm	Stops applying menus inside the factory; returns base bar button item only.
ios/gamma/stack/header/RNSStackHeaderContentFactory.h	Updates docs to reflect menu application moving out of the factory.
ios/gamma/stack/header/RNSStackHeaderConfigDataProviding.h	New protocol for exposing config + children to the coordinator.
ios/gamma/stack/header/RNSStackHeaderConfigComponentView.mm	Wires provider/delegates into coordinator; routes invalidations to selective coordinator APIs.
ios/gamma/stack/header/RNSStackHeaderConfigComponentView.h	Declares protocol conformances and exposes config properties + children.
apps/src/tests/single-feature-tests/stack-v5/test-stack-header-selective-updates-ios/scenario.md	New manual test scenario steps for selective updates validation.
apps/src/tests/single-feature-tests/stack-v5/test-stack-header-selective-updates-ios/scenario-description.ts	Scenario metadata for the new SFT.
apps/src/tests/single-feature-tests/stack-v5/test-stack-header-selective-updates-ios/index.tsx	New SFT implementation exercising selective updates and menu behaviors.
apps/src/tests/single-feature-tests/stack-v5/index.ts	Registers the new SFT in the stack-v5 scenario list.

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[kmichalikk]

This is so iOS implementation works the same as android implementation