feat: add snprintf/sprintf hook

[codesensei-tushar]

Add SnprintfHook implementation

Fixes #318

Changes

• Implement snprintf/sprintf hook using Python's native % formatting
• Handle pointer dereferencing for %s format specifiers by reading strings from emulator memory
• Support signed/unsigned integer conversion for %d, %i, %u, %x, %X, %o
• Support width and precision modifiers (e.g., %10s, %.5s, %08x)
• Handle both sprintf(buf, fmt, ...) and snprintf(buf, size, fmt, ...) variants

Testing

Tested with this sample C file: test_snprintf_comprehensive.c

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[williballenthin]

please add some tests that demonstrate this routine works the way we think it does

[codesensei-tushar]

Thanks for the review! I'd like to clarify what kind of tests you're looking for:

• Unit tests - pytest tests that mock the emulator and verify SnprintfHook._prepare_args() and .call() work correctly with various format specifiers.

• Integration tests - Tests that run FLOSS on an actual binary (like the C test file I shared) and verify decoded strings are extracted.

[codesensei-tushar]

Added tests/test_snprintf_hooks.py in the latest commit!
All 11 tests passing. Let me know if you'd like any additional test cases!

[williballenthin]

thank you @codesensei-tushar!

the unit tests look good

[codesensei-tushar]

I did run black previously, but it might not have run properly. In the latest commit, I've verified that all pre-commit checks:

The mypy check was failing due to a pre-existing issue in floss/utils.py (unrelated to the SnprintfHook changes). The error was a false positive — the code is correct, but mypy couldn't verify it statically due to the dynamic **kwargs pattern used for platform-specific mmap arguments:
Without a type annotation, mypy sees **kwargs and can't determine whether it contains valid arguments for mmap, so it flags it as an error. I added # type: ignore[arg-type] to suppress this false positive.