Function populate_codebase 

pub fn populate_codebase(
    codebase: &mut CodebaseMetadata,
    symbol_references: &mut SymbolReferences,
    safe_symbols: AtomSet,
    safe_symbol_members: HashSet<SymbolIdentifier>,
)

Populates the codebase metadata, resolving types and inheritance.

This function processes class-likes, function-likes, and constants to:

• Resolve type signatures (populating TUnion and TAtomic types).
• Calculate inheritance hierarchies (parent classes, interfaces, traits).
• Determine method and property origins (declaring vs. appearing).
• Build descendant maps for efficient lookup.

TODO(azjezz): This function is a performance bottleneck.