Fix ThemeProvider context mismatch in shadow-root modal providers

[bunnybones1]

Problem

Some integrations hit:

useTheme must be called within a ThemeProvider

while using @0xsequence/connect, @0xsequence/checkout, and @0xsequence/wallet-widget together.

Root cause

ShadowRoot (in @0xsequence/connect) always created ThemeProvider internally.
checkout and wallet-widget render design-system components in that shadow root. Depending on module resolution/install shape, this can cause a React context/module split and make useTheme resolve outside the expected provider instance.

Fix

1. Added render-prop support to ShadowRoot so callers can receive the shadow container.
2. Kept existing behavior for non-function children (backward compatible).
3. Updated providers to mount their own ThemeProvider inside ShadowRoot using the passed container:
   • SequenceConnectProvider
   • SequenceConnectInlineProvider
   • SequenceCheckoutProvider
   • SequenceWalletProvider

Why this works

It removes the implicit cross-package provider coupling and ensures modal trees are wrapped by the provider instance associated with the package rendering those components.

Notes

• This addresses the runtime theme-context error without requiring app-level @0xsequence/design-system setup.
• Formatting checks pass on touched files.
• Workspace typecheck currently has pre-existing monorepo resolution issues unrelated to this patch (@0xsequence/hooks / @0xsequence/connect module resolution).

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