Replace direct `.count()` uses with `count_seconds` or `count_microseconds` where the unit matters for logs and serialized timestamps.
Update `p2p_handshake` fuzz bounds to express the same seconds conversion explicitly.

Use `Ticks` in mempool tracepoints and Qt ping time formatting to avoid manual duration casts and conversions.
Update `scheduler_tests` to use `Ticks` for the remaining job delta calculation.