mars: give L.U.N.A. direct git+tea access to the homelab repo

Provisions a dedicated PR-tier gitea account (luna) with branch protection
restricting master push/merge/approve to darman only, then wires git and
tea directly into the hermes-agent container (mounted from the host's Nix
store, credential-store + tea login set up by a host-side prepare oneshot,
repo cloned inside Hermes's own writable sandbox root at
/opt/data/workspace/homelab). Replaces an earlier standalone MCP-server
approach, scrapped in favor of direct CLI access for simplicity.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011FHr5ug9pu8q4XPrRkFnzJ

hosts/mars/secrets.nix

@@ -35,4 +35,16 @@
     TELEGRAM_ALLOWED_USERS=15151223
     HERMES_DASHBOARD_OIDC_CLIENT_SECRET=${config.sops.placeholder.hermes_dashboard_oidc_client_secret}
   '';
+
+  # luna's own gitea push token (services/dev/gitea.nix provisions the
+  # account + PR-tier repo access on jupiter; this is the per-user token
+  # generated once via `gitea admin user generate-access-token --username
+  # luna --scopes write:repository,read:user` on jupiter — read:user is
+  # required, `tea logins add` fails without it). Read directly by
+  # hermes-agent.nix's prepare-dirs oneshot (default root:root owner is
+  # fine — that oneshot already runs as root) to set up a git
+  # credential-store file and a `tea` login, both written into hermesHome
+  # so they're visible inside the container at /opt/data/....
+  # restartUnits re-provisions both on rotation, without a full mars deploy.
+  sops.secrets.gitea_luna_token.restartUnits = [ "hermes-agent-prepare-dirs.service" ];
 }