fix: v0.3.2 – MultiSeriesChart, ThemeToggle, scroll lock and picker fixes

[Shewart]

Summary

Backports the non-breaking fixes from main (#38) to the 0.3 line and releases 0.3.2.

• MultiSeriesChart threw on every render in the package (duplicate ChildContent, unknown Subtitle on ApexChart). It now renders inside the same card as Chart.
• window.ShellUI for package users: a Blazor JS initializer loads shellui.js at startup. This fixes ThemeToggle not changing the theme, dialog/sheet/drawer scroll lock, and close-on-scroll. Adds the missing addClassToDocument, removeClassFromDocument and setupFileDrop.
• ThemeToggle no longer keeps a static instance list shared across Blazor Server users. Toggles follow the page's dark class and stay in sync.
• DatePicker / DateRangePicker popover gets a width; DataPicker / MultiSelect options are left-aligned.
• Removed the RCL template leftovers from the package.
• New bUnit test renders every package component and fails on parameter-binding errors.
• Version 0.3.2: props, fallback versions, docs, package README links, release notes.

Not included: the Calendar SelectedDateChanged type change (breaking, 0.4 only).

Verification

• dotnet build 0 warnings, 156 tests pass.
• Packed ShellUI.Components.0.3.2.nupkg: the JS initializer ships and the leftovers are gone.
• The same fixes were verified in a fresh app with a packed package on main (fix: package component bugs (MultiSeriesChart, ThemeToggle, scroll lock, pickers, Calendar binding) #38).