refactor(bottom-navigation): align with MD3 navigation behavior

Refactor BottomNavigation to improve Material Design 3 compliance, remove problematic children patterns, improve performance characteristics, and modernize the public API.

**Problems**

- Current API relies heavily on children composition in ways that are difficult to optimize
- Internal layout logic is tightly coupled to arbitrary child structures
- MD3 behaviors and visuals are not fully aligned with current Material guidelines
- Rendering performance can degrade in large lists or frequently updated screens
- Type safety and discoverability of the API can be improved
- The component has inconsistent behavior between platforms and edge cases

**Focus Areas**

- Improve active indicator implementation
- Improve shifting behavior
- Improve lazy screen rendering integration
- Improve badge handling

**Performance Opportunities**

- Reduce navigation item rerenders
- Improve animated transitions
- Optimize route updates

首先定位 BottomNavigation 的实现及其当前 API，然后检查活动指示器、移位、延迟屏幕渲染、徽章和路由更新是如何处理的。将现有行为与 Material Design 3 相关的导航指南进行比较，并确定定义重构完成标准所需的测试。

由索引模型根据 Issue 内容生成。