v0.16.2

Raises the flopscope minimum to 0.12.3, including the 0.12.2 billing and
symmetry corrections and the 0.12.3 truncated-SVD rank pricing. Local FLOP
counts can change for affected estimators; remeasure candidates with the
updated meter. The development flopscope-server floor moves in lockstep.

Fix

• scoring: consume exactly the requested streaming-dataset prefix, so an
  unavailable extra row cannot abort a complete load. Validate restored MLP
  width and depth against the contest specification for both streaming and
  materialized datasets, with an indexed diagnostic for incompatible rows.
• deps: require flopscope 0.12.3 for local evaluation and refresh the lockfile.

Documentation

• Explain corrected broadcast/dtype billing, symmetry handling and truncated
  SVD; correct stale operation-cost guidance and refresh the Participant Guide
  pin to the merged starter kit.