test: render V2 sidebar with resolved theme

[danyel117]

Summary

• use the real V2 ResolvedTheme in sidebar tests
• cover native OpenTUI rendering with RGBA leaf tokens instead of string-only theme mocks
• add the matching V2 theme package as a development dependency

Root cause

OpenTUI throws Expected ArrayBufferView but received Cell to a pointer when a theme color group is passed to fg. The runtime leaf-token fix is already present in 0.1.38, but the global TUI/CLI configs remained pinned to 0.1.31 and the tests used simplified strings that could not reproduce this failure.

Validation

• bun run lint
• bun run typecheck
• bun test (213 pass)
• bun run build
• bun run pack:dry-run