fix(faster-whisper): cast segment timestamps to int after multiplication (#9674)

`int(x) * 1e9` returns a float because `1e9` is a float literal, but
TranscriptSegment.start/end are integer protobuf fields. This caused
every transcription request to fail with:

  TypeError: 'float' object cannot be interpreted as an integer

Multiply first, then cast — `int(x * 1e9)` — to get an int as required.