## Why
Compression metrics do not distinguish startup runs from runs requested through
`rollout/compress`, making their outcomes indistinguishable by entry point.
## What changed
Pass `RolloutCompressionTrigger` from startup and RPC callers through the
compression worker. Add a `trigger` tag with `startup` or `rpc` to run, file,
scan-error, and temporary-file cleanup metrics, including durations, byte counts,
and compression ratios.
GitOrigin-RevId: f23d9da791b666a7311f2323f6bead6570067798