SUCCESS

Implementation complete. All tests pass (8/8 test functions, 11/11 test cases).

Automatic import detection and injection working for:
- os (ReadFile, WriteFile, Open, etc.)
- strconv (Atoi, ParseInt, etc.)
- encoding/json (Marshal, Unmarshal)
- io (ReadAll)
- fmt (via needsFmt flag)

Source mappings correctly adjusted for import block offsets.
