List the Embree headers individually in binding.yml

[jcant0n]

The first CD run refused to publish, and it was right to:

- vendored: v4.4.1
- resolved: v4.4.1 (up to date)
- EmbreeGen/Headers/embree4 (c-header): updated
Result: sources changed.

::error::upstream moved and Evergine.Bindings.Embree/runtimes exists, but no native
artifacts were supplied. Committing now would ship a managed layer built from one
revision against libraries built from another.

The release had not moved. The directory source had. A directory is compared by hashing
everything under its path, and this tree can never match upstream's for two reasons:
include/embree4 also carries eight .isph files for ISPC that this binding does not use, and
it carries a rtcore_config.h that upstream does not have at all, because CMake generates it.

The visible cost was a CD that could not publish. The quieter one is that binding-updater
would have read that same report every month, concluded upstream had moved, and opened a pull
request that regenerated nothing.

Listing one entry per header makes each source hash as a single file, so what is not listed is
simply not compared — rtcore_config.h included. Verified all nine match upstream at v4.4.1
byte for byte.

[github-actions]

API gate: additive

Every symbol that existed still exists, unchanged. Nothing that compiled before stops compiling.

Target framework	Added	Removed
net10.0	+0	-0

_{Enum and constant values are part of the measured surface: a renumbering keeps compiling and sends the wrong number to the driver, so it counts as a removal.}