feat: publish Gamertan Tend preview source

Sanitized root snapshot from private source commit a72903c63e1753f9e6ffbf40453c0830bdfc05c5 and tree 295641e67eef5979da76746d8ae271249568263e. Private development history and workflows are excluded by the exact allowlist.

AI-assisted: OpenAI Codex helped implement, test, and audit this preview.
Signed-off-by: Cole Speelman <crspeelman@gmail.com>

RELEASE.md

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+# Preview release policy
+
+`v0.1.0-preview.1` may be published only after one identical candidate Tend
+binary has successfully completed maintenance releases for Gamertan and the
+Sandwich Hime website, including injected-failure restoration and explicit
+rollback proof. The August 14, 2026 campaign met that gate; the scoped,
+sanitized record is in `docs/DOGFOOD_EVIDENCE.md`.
+
+Before a preview tag:
+
+1. Run `./scripts/verify.sh` from a clean pushed private-development commit.
+2. Review dependency, license, race, filesystem, archive, and rollback evidence.
+3. Export the exact allowlisted public tree into a new root commit.
+4. Verify canonical Gitea and GitHub discovery trees are byte-identical.
+5. Sign the canonical Gitea tag and attach checksums and an SPDX SBOM.
+6. Verify a fresh public checkout before advertising installation.
+
+The release tag and attached candidate must be built from the final reviewed
+source commit. Documentation-only changes after the recorded campaign require
+one final identical-candidate maintenance pass before tagging.
+
+The canonical public origin is `ssh://git@gitea.speelman.ca:2222/gamertan/tend.git`.
+GitHub is a read-only discovery snapshot. Private development history is not
+published or merged into either public history.