docs: verify no padding issues in serialized structs

[gdellis]

Summary

Audit of structs serialized via memcpy in the codebase for issue #63.

Audit Results

BLE structs (already fixed in PR #52):

• BleLocationData (17 bytes) - uses #pragma pack(push, 1), static_assert added
• BleAlertData (18 bytes) - uses #pragma pack(push, 1), static_assert added

GPS structs (no issue):

• GpsData - Contains only C++ fundamental types (double, uint8_t, uint64_t), no memcpy serialization found. Used internally, not serialized over wire.

LoRa structs (no issue):

• LoRaPacket - Contains fixed-size array (uint8_t data[255]), no struct memcpy. Uses manual byte copying in send/receive methods.

Manual serialization (verified correct):

• try_lora_send() in state_machine.cpp manually copies fields with known sizes (4-byte int32, 2-byte battery, etc.) - no struct padding concern
• try_ble_fallback() populates BleLocationData field-by-field, not via memcpy

Conclusion

No additional structs need #pragma pack. The BLE structs were the only ones serialized via struct memcpy, and those are already fixed.

Closes #63

[gdellis]

This PR audited other serialized structs for padding issues (issue #63). The audit found no additional issues beyond those already fixed in PR #52.

The branch has been rebased onto current main and no additional changes are needed. Closing as duplicate of the fixes already merged.