Ignore imported library relations that point outside the
package or self-link a file on the v3 import path. Delete
leftover cross-team and self relations from file_library_rel
and their matching file_library_sync rows with migration
0158, sync rows first.
Move the get-files-rels SQL to a var, without behaviour change.
Cover the write-side invariants with state-based tests:
tampered manifests, package containment, self links and the
migration cleanup.
AI-assisted-by: deepseek-v4.1-flash
AI-assisted-by: muse-spark-1.3-contributor
0b8a428d6b