Ownership conventions

Zig has no borrow checker — ownership is convention, not enforcement. The rule that makes manual memory livable: whoever calls init is responsible for calling deinit. A function that allocates and returns ownership uses errdefer to clean up on failure; the caller then defers the deinit. A function that borrows takes a slice or pointer and never frees. Once these conventions become reflex, manual memory feels almost as easy as garbage collection — minus the runtime cost.