Module mode 

Compatibility mode resolution.

Precedence ladder (FR-021, AD-010, HINT-004):

1. Explicit --strict flag wins over everything.
2. RUSTY_SPONGE_STRICT=1 env var (any truthy value).
3. argv[0] basename equals sponge (after .exe strip on Windows).
4. Default mode.

Functions

resolve

Resolve the compatibility mode from CLI flag, env var, and argv[0].