Fixes/tabbar focus shifting

[usmanvrtx]

Description

This PR improves TV focus scrolling and TabBar navigation, and adds bounded content sizing for TV ListViews.

Related Issue

N/A

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update
• Refactoring

What Has Changed

TV focus scrolling

• Preserved legacy visibility scrolling for existing widgets.
• Added route-scoped tracking of the active vertical scrollable.
• Added resetScrollOnFocus for resetting page scroll when a configured widget receives focus.
• Cleared remembered scrollables when routes are removed, replaced, or popped.
• Preserved vertical and horizontal scrolling behavior without changing focus row/order semantics.

TabBar focus behavior

• Added revealTabBarOnFocus as an opt-in TV option.
• Preserved legacy behavior by default.
• When enabled, focusing a tab reveals the enclosing TabBar instead of only the tab.
• Added horizontal tab-strip scrolling.
• Respects verticalScrollPadding.
• TabBar autofocus now follows the configured autofocus value.
• Added regression coverage for legacy TabBar reveal behavior.

ListView sizing

• Added minHeight support to ListView styles and schema.
• Added bounded content fitting for:

  shrinkWrap: true
  minHeight: ...
  maxHeight: ...

• ListView height is calculated as:

  clamp(contentHeight, minHeight, maxHeight)
  

• Preserved the existing TV scrollbar Row layout.
• Removed the previous fitContent/minHeight measurement implementation in favor of the new bounded sizing behavior.

Usage

ListView:
  styles:
    minHeight: ${device.height * 0.2}
    maxHeight: ${device.height * 0.6}
    shrinkWrap: true
    flexMode: none
    tvOptions:
      row: 1
      order: 0
      revealTabBarOnFocus: true

For scroll reset:

tvOptions:
  resetScrollOnFocus: true

How to Test

cd modules/ensemble

flutter test test/widget/list_view_core_test.dart

flutter test test/widget/tab_bar_index_test.dart \
  --plain-name 'TabBar does not reveal the whole bar unless enabled'

flutter analyze \
  lib/layout/list_view.dart \
  lib/framework/tv/tv_scrollbar_widget.dart

Also verify the ListView and TV focus behavior on the target TV host layout.

Screenshots / Videos

N/A

Checklist

• Focused tests pass
• Schema JSON validation passes
• git diff --check passes
• Tested on the relevant TV platform
• Added dedicated ListView sizing regression tests
• No new analyzer warnings introduced