WIP: TDF/OCAF bindings PoC

[Ben-PH]

Adds initial Rust bindings for OCCT's TDF subsystem as groundwork for
TNaming-based feature history in CAD-L.

What's in:

• TDF_Data construction and root label access (via HandleTdfData)
• TDF_Label child creation and null check
• TDF_Transaction open/commit/abort with delta return for undo
• 'doc lifetime enforcement between TdfData and TdfLabel

What's missing before this is contribution-ready:

• TNaming_Builder bindings (Generated, Modify, Delete, Select)
• TdfDelta safe wrapper type (currently leaks UniquePtr)
• Undo test against observable state change
• build.rs link additions for TDF/TNaming libraries (currently implicit)

Disclaimer: Much of this work was done with a lot of heavy lifting coming from LLM assistance, but without LLM directly touching the codebase.