Merge-with-key: decrypt exported posts using original identity seed, re-create
under current identity with prior_author in BlobHeader for provenance tracking.
Download page restructured with stable (v0.4.4) + beta (v0.5.0-beta) sections.
Version bumped across all crates.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>