loadbearer v1.6.0

How old is this machine? Nothing on a PC records when it was built, so
loadbearer now reasons from what does carry a date or a count, and says how
far each piece of evidence goes. No measurement changes: 1.5.x scores and
result files are directly comparable, and nothing here touches a grade.

• An age estimate. A machine can't be older than its CPU, so the launch of
  the CPU's generation is a floor on when it was built — "built Jan 2023 or
  later, at most 3.8 years old". The firmware date isn't a bound either way,
  since an update moves it forward, but within a year of the CPU's launch it is
  probably what the machine shipped with, and the estimate says so. info
  shows it as an Age section, a scored report and the results screen as an
  AGE block. The launch table covers Intel Core from the first generation
  through Core Ultra Series 3, the N-series and Atom-class Celeron/Pentium,
  Ryzen, Ryzen AI, Threadripper, EPYC, Apple M1–M5 and Snapdragon X; a CPU it
  doesn't know — a Xeon, a Core 2 — gets no estimate rather than a guess.
• Drive health, and the drive's hours as an odometer. Each NVMe drive's
  SMART / health log and each SATA drive's ATA Device Statistics: power-on
  hours, power cycles, endurance used, data written, and for NVMe spare,
  unsafe shutdowns, media errors and the critical-warning flags. SATA is read
  from the statistics log rather than SMART attribute 9, whose unit is whatever
  the vendor chose. On Windows it needs no elevation; on Linux the device nodes
  are root-only, so an unprivileged run simply leaves it out. Checked against
  smartctl / nvme smart-log on Windows NVMe, Linux NVMe and Linux SATA;
  Windows SATA has not yet been tried on hardware.
• Drive hours that measure working time are called out. Some SATA SSDs
  stop counting in low-power idle — one laptop's reported 175 hours over 4,314
  power cycles and 17 TB written. A drive averaging under fifteen minutes per
  power cycle is marked "likely undercounted" and its hours aren't read as time
  in service.
• System model and firmware in the inventory: "Dell Inc. Latitude 7440",
  or Lenovo's marketing name beside its type code, and the BIOS version and
  release date. Not per-unit — every machine of a model reports the same
  strings — and no drive serial is read.
• All of it is in the result file, for a fleet collector: machine.age in
  machine-readable form (YYYY-MM dates, whole months, hours), plus
  machine.firmware and machine.drives. New optional fields under
  loadbearer.result/1, so nothing reading 1.5 files breaks. The values in
  machine.age come from the launch table, which is data rather than API and
  will be corrected and extended in later releases (see VERSIONING.md); key
  on cpu_launched and max_age_months, not the wording.
  loadbearer-fleet 0.7.0 reads
  them.

What's Changed

• build(deps): bump actions/attest-build-provenance from 2 to 4 in the github-actions group across 1 directory by @dependabot[bot] in #2
• build(deps): bump the cargo group across 1 directory with 6 updates by @dependabot[bot] in #7

Full Changelog: v1.5.2...v1.6.0