Add ENHO creation for XH, class enhancements, and BAdI

[Augusto42]

What changed

• adds a dedicated CreateEnhancement Go API, MCP tool, and vsp enhancement create CLI
• creates source-code plug-ins (HOOK_IMPL), class enhancements (CLASENH) with an optional new method, and BAdI implementations (BADI_IMPL)
• reads authoritative subtype metadata from ENHHEADER, generated class-enhancement includes, and structured BAdI metadata
• extends the ZADT_VSP bridge with explicit create/describe actions, validation, SAP-owned save/activation, rollback, and active read-back
• documents CLI and MCP usage and updates the support matrix

Why

WriteSource cannot safely create an ENHO because source text does not identify the host, exact anchor, class, enhancement spot, BAdI definition, or implementation class. Older ADT search on classic systems can also mislabel class and BAdI enhancements as XH.

For transportable packages on NetWeaver 7.52, enhancement subobject text persistence dropped the approved CTS task and attempted to open an interactive transport dialog in a background worker. The bridge now propagates the task through SAP's standard CTS memory contract.

Validation

• go test ./...
• go vet ./...
• ABAP bridge syntax check and activation on an isolated SAP NPL 7.52 lab
• synthetic end-to-end creation and active read-back for XH, class enhancement, and BAdI in both local and transportable packages
• CTS ownership verified after transportable creation
• repository diff checked to contain only synthetic examples and no customer data