v0.17.0

Breaking — sandermuller/boost-core floor raised to ^0.18

The sandermuller/boost-core constraint narrows from
^0.16 || ^0.17 || ^0.18 to ^0.18 || ^0.19, dropping support for
boost-core 0.16 and 0.17.

This package now uses boost-core's .config/ layout — config at
.config/boost.php, sync manifest under .config/boost/. Config-path
resolution arrived in boost-core 0.17, but the manifest relocation from
root .boost/ to .config/boost/ only landed in 0.18, so 0.18 is the
floor where the .config/ layout is fully consistent.

If your composer.json requires boost-core below ^0.18, bump it:

composer require sandermuller/boost-core:^0.18

Already on boost-core ^0.18 or later? No action needed. See
UPGRADING.md
for the full migration note.

Changed

• Dogfood config moved to .config/boost.php. This repo's own boost
  config now lives under .config/ instead of the repo root, demonstrating
  the layout boost-core 0.18+ supports. boost-core resolves either location
  (root boost.php or .config/boost.php) — but not both at once, or it
  fails loud. Consumers may relocate their own config the same way; a root
  boost.php keeps working unchanged.
• stolt/lean-package-validator widened to ^5.7 || ^6.0, allowing
  consumers to resolve the 6.x line.

No source/API changes — the package's public surface is unchanged. This
release is constraint and configuration-layout only.

Full Changelog: 0.16.3...0.17.0