Track allocator and free provenance

[itsfuad]

Goal

Track allocator provenance for allocation-owning *T values and enforce correct deallocation.

Current Model

• *T owns allocator-backed storage and moves by default.
• rawptr is untyped, non-owning runtime address data.
• free(owner) consumes a valid *T and lowers to deallocation.
• Live owned values receive automatic recursive destruction at scope exit, return cleanup, overwrite, and discarded-temporary boundaries.

Progress

• PR Add raw allocator bootstrap and attr checks #37 added core:allocator libc-backed Malloc / Free declarations.
• PR Implement scalar copy and runtime ownership semantics #48 adds explicit free lowering, automatic destruction plans and drop glue, static use-after-move prevention, overwrite cleanup, temporary cleanup, and ABI validation for runtime free reuse.

Remaining Work

• Track allocation origin and allocator instance on every *T.
• Reject deallocation through a different allocator.
• Define allocator provenance carried by owning interface erasure (*Iface).
• Extend validation beyond initial selected-program-allocator ABI.

Validation

• Semantic tests for valid free, invalid operands, use after consume, and ownership joins.
• Runtime fixtures proving exactly-once cleanup.
• ABI tests for compatible and incompatible externally linked free declarations.