## Why
Hash-based sharding does not account for differences in test duration. Use estimated test time to balance the Windows Bazel workload across shards.
## What changed
- Add checked-in duration weights and a deterministic selector that assigns the longest targets first to the least-loaded shard.
- Assign every queried target exactly once, default missing weights to one second, and ignore stale weights.
- Run queries and selection in the foreground so failures stop the job before tests run with a partial target list.
- Emit LF-delimited target labels for Git Bash and report estimated shard loads on stderr.
## Testing
Add seven passing selector tests covering deterministic coverage and balancing, missing and stale weights, invalid inputs, duration-file overrides, and CLI output. Run them on the first Windows CI shard.
GitOrigin-RevId: d415ae093bfe57794ee53a2eb9d712022202dad8
