fix: align search results with theme colors

[Kyle-Structure]

Fixes #38

Summary

• Route the search results pane through sidebar/list theme variables with editor/input fallbacks.
• Use list.highlightForeground for search-result match highlights so the left results list behaves more like VS Code's native Search view.
• Keep editor find-match highlighting scoped to the preview code pane.

Verification

• git diff --check
• npm run compile

Note: npm run lint cannot run in the current repository because ESLint does not find a configuration file.