a67271b08c
- Add statement for function-level deferred execution - Deferred expressions run in LIFO order on function exit (return or implicit) - Bootstrap: desugar defers in hir_lower.nim (inject before return + end of func) - Selfhost: emit defers in c_backend.bux via CEmitter defer stack - Both: add tkDefer token, skDefer AST node, hDefer HIR node - Parser, lexer, sema, token files updated in both bootstrap/ and src/