fix(hierarchical, jdk): capture cast types, instanceof bindings, and new-object type args in source AST

[deer]

Fixes three source-tree capture gaps in JdkExpressionConverter and cleans up a wasteful double-traversal in HierarchicalTypeDescriptor.

• visitTypeCast: Resolves the cast target type via trees.getTypeMirror() instead of always emitting UnknownTypeUsage. Falls back to UnknownTypeUsage when type context is unavailable.
• visitInstanceOf: Captures pattern-binding variable names from Java 16+ instanceof patterns (e.g. obj instanceof String s). Added Optional bindingVariable to InstanceOf.
• visitNewClass: Splits parameterized class expressions (e.g. new ArrayList()) into a bare type name and a separate type-arguments list instead of collapsing everything into a single identifier string. Added Stream typeArguments to NewObject. Note: anonymous class bodies remain untracked (separate architectural concern).
• formsDiamondPattern: Collects parents() into a set once rather than calling the stream twice.

Each converter fix is covered by a new integration test in ExpressionCaptureFidelityTests.