chore(submodule): bump subx-core to f3829ba (v1.0.0 tag target)

The tag's first publish attempt failed in CI's dry run: the committed
standalone Cargo.lock was a stub, so cargo publish had to lock 401
dependencies and refused the dirty tree. f3829ba carries the complete
regenerated lockfile; the re-tagged v1.0.0 published successfully.
subx-core 1.0.0 is now on the sparse crates.io index.

Author: jim60105