Add SD SPI CMD24 write support

[jhlagado]

Summary

• implement CMD24 single-block write path in SD SPI emulator
• add unit test covering data token + CRC + write response

Testing

• not run

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[jhlagado]

Review: SD SPI CMD24 write support\n\n### Summary\n- Implements CMD24 (single-block write) in the SD SPI emulator.\n- Adds a unit test for data token, CRC, and write response.\n\n### Code Review\n- Write state machine is clear and robust: handles token, buffer, CRC, and commit.\n- logic is safe and bounds-checked.\n- Test covers the full write path and verifies image mutation.\n- refactor improves clarity for both read and write.\n\n### Suggestions\n- Consider adding a test for high-capacity (SDHC) write addressing.\n- Add a comment on the data response token (0x05) for future readers.\n- No functional issues found.\n\nLGTM. Ship it.\n\n_Reviewed via gh CLI as requested. Summary also posted in chat._