Refactor: Aggressively purge over-engineered semantics and code bloat

[Haerbin23456]

Summary

This PR addresses severe over-engineering introduced in previous refactoring rounds. It aggressively cleans up unnecessary semantic constants, deeply nested logic, and pedantic static analysis checks, significantly reducing code bloat.

• Removed PackageManifestSemantics.cs & ComRegistrySemantics.cs entirely
• Inlined meaningless UI semantic strings (BenchmarkSemantics.Category, Type, FilterCategory, etc.)
• Inlined trivial string/character literals (e.g. {, }, -, command, MUIVerb, Icon) back into actual scanning and parsing logic for readability.
• Removed aggressive QualityChecks assertions that forced developers to use convoluted semantic constants instead of standard C# literals (saving ~400 lines in the check file alone).
• Deduplicated RegistryScanner logic, merging repetitive global/directory target scans into shared helper methods, eliminating ~70 lines of boilerplate.

Verification

• Local dotnet build succeeds.
• scripts/verify_local.bat quality checks pass (using the new, relaxed semantic rules).
• No functionality changes; this is purely a structural and code health revert.