v0.1.0-alpha.5: benchmark death counts

Raid benchmark reports now show connected, dead, and death-unknown clients at each measured window close. Counts include login snapshots, later health updates, ghosts, revival, and disconnects.

Report schema v3 adds the two counts. Older reports keep missing values unknown. The additive ramp is unchanged.

Includes PR #7. Reviewed commit a8398ba passed Linux, macOS and coverage checks, 62 local tests, strict clippy and release builds.

Known limitation found after review: a sparse login CREATE that omits zero health or player flags can leave the initial death state unknown. Corrected in alpha.6 by PR #8. Later partial updates remain supported.