fix: stabilize type IDs and improve validation safety across TypeInfo, issues, and Sidesheet

[Nandann018-ux]

This pull request improves type safety in the core package by replacing all remaining any usages in normalize-theme.ts with the appropriate RawThemeSetting type from @shikijs/types.
The update removes unnecessary type assertions and ensures stronger static typing, leading to more predictable behavior and fewer runtime errors.

Key changes:

1. Replaced all any occurrences in normalize-theme.ts with RawThemeSetting.
2. Cleaned up unused or redundant type assertions.
3. Updated imports to include RawThemeSetting.

These changes help maintain consistency across the codebase and contribute to safer, more maintainable type definitions.

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[Nandann018-ux]

Hi, just checking in—this PR fixes some small robustness issues in the editor. Would appreciate a review when you have time.