Fix WASM wrapper systematic issues

- Standardize error handling to use safe_strdup consistently
- Add input validation to wasm_fingerprint function
- Improve memory management with proper bounds checking
- Replace hardcoded scan responses with proper token parsing
- Add comprehensive allocation failure handling
- Fix buffer overflow prevention in all functions
- Include input query in scan error messages for test compatibility

All 45 tests now passing successfully.

Co-Authored-By: Dan Lynch <pyramation@gmail.com>

Author: devin-ai-integration[bot]