CVE-2026-52808: Gogs's write-level collaborators can mutate admin-only repository settings via API

Three API endpoints — PATCH /api/v1/repos/:owner/:repo/issue-tracker, PATCH /api/v1/repos/:owner/:repo/wiki, and POST /api/v1/repos/:owner/:repo/mirror-sync — are gated by reqRepoWriter() rather than reqRepoAdmin(). The equivalent operations in the web UI sit behind reqRepoAdmin, which requires AccessMode >= AccessModeAdmin. A write-level collaborator (who has AccessMode == AccessModeWrite < AccessModeAdmin) can therefore call these API endpoints directly to disable the native issue tracker or wiki, inject attacker-controlled external tracker/wiki URLs that redirect all repository visitors, or trigger mirror sync — none of which they are authorized to do.