fix(tui): inherit elevated tool theme

[jlongster]

Summary

• add a scoped theme context provider for nested component surfaces
• render block tool content and status badges with the elevated theme context
• preserve the parent surface color for the block border

Testing

• bun typecheck in packages/tui
• bun test test/cli/tui/inline-tool-wrap-snapshot.test.tsx in packages/tui
• OpenCode Drive snapshot of a background shell block

[jlongster]

Before and after

Before	After

The elevated theme now reaches nested block content, including the Background status badge, while the left border retains the parent surface color.