Fix: add endian byte-swap for portable --fried import/export

[Thunder-Blaze]

Issue

• Fixes: FIXME at cmd_export.cpp:34 and cmd_import.cpp:79

Description

The --fried flag on strfry export and strfry import enables a fast binary format that embeds the packed event representation directly. The packed format stores created_at, kind, and expiration as raw uint64 values in native byte order. This means fried data exported on a little-endian system can't be imported on a big-endian one - strfry currently throws a hard error on non-LE systems.

This fix defines the fried wire format as always little-endian and adds friedSwapEndian() which byte-swaps the three uint64 fields (at offsets 64, 72, 80) between native and LE. Using if constexpr, the swap is a compile-time no-op on little-endian systems - zero runtime cost for x86/ARM-LE.

Testing

• Haven't been tested because I do not own such a system but I have properly reviewed the code properly and believe it will work
• Can wait for this to get merged after I can somehow check this on any big-endian device