Coalesce component renders during Blazor WebAssembly startup #1

[yasmoradi]

Summary

Adds an opt-in render-coalescing mechanism to AppComponentBase that collapses a burst of StateHasChanged calls during the app startup window into a single trailing render. It is active only on Blazor WebAssembly (where startup rendering is the bottleneck) and disabled by default.

Changes

• New AppComponentBase.Rendering.cs: overrides ShouldRender to debounce renders during the startup window. Suppressed renders (re)arm a single trailing render so the final startup state is guaranteed to paint. Tunable via CoalesceRendersDuration (default 3s, measured from app start) and CoalesceRendersWindow (default 300ms quiet period). Only runs when AppPlatform.IsBrowser; everything else renders normally.
• AppComponentBase.cs: adds a DisposeRenderCoalescing() partial invoked from DisposeAsync so the coalescing timer is always released; the whole feature stays isolated in its own file and compiles away when absent.
• Opt in (CoalesceRenders => true) for AppShell, Header, NavBar, HomePage, and AppAiChatPanel.

Related Issue

This closes #1

[yasmoradi]

Superseded: opened on upstream as bitfoundation#12754. This fork PR was created by mistake.