Ghost FTP 0.95.51 — Release governance hardening (UNRELEASED Preview)

Previous published release: v0.95.50. Baseline main SHA: 5c5e821.

Changes

Harden SSH known_hosts replacement against symlinks, Unix hardlinks and changed backing file identities; add preservation and valid-path regression tests.
Restore automatic Preview publishing after every main change (no native-build path filters), with all six exact-SHA CI gates required.
Enforce a unique version on every merged change and block the next PR until the preceding main version has a published release, retaining full cross-platform metadata synchronization.
Stage a draft and verify checksums, complete remote digests, expected asset count and immutable source tag before automatic Preview prerelease publication.
Refuse modifying already-public releases. Correct public v0.95.50 documentation discrepancy.

Android persistent Play upload signing and device upgrades.
macOS FTPS/SFTP, Developer ID signing, notarization and Gatekeeper QA.
Windows signing and Linux real package launch; integrity, long-duration, cloud, UI and security acceptance on supported targets.
Stable/FINAL/1.0.0 promotion is not authorized.