Adds a per-instance DNS-01 mode to the Caddy role for mesh/LAN-only hosts that
cannot satisfy HTTP-01. Default behaviour (vanilla caddy:2 + HTTP-01, what askari
runs) is unchanged.
- reverse_proxy__acme_dns_provider: "" (HTTP-01) | "gandi" (DNS-01)
- reverse_proxy__image: override to the custom caddy-gandi image for DNS-01
- Caddyfile gains a global `acme_dns gandi {env.GANDI_BEARER_TOKEN}` block
- the PAT (vault.gandi.pat) renders into a host-only 0600 env file (no_log),
loaded by compose only when DNS-01 is enabled
Verified: the custom image issues a real wildcard cert (*.dns01test.wingu.me)
end-to-end against LE staging via Gandi DNS-01; `caddy validate` accepts
`acme_dns gandi` on the custom image and rejects it on vanilla caddy:2. Molecule
(HTTP-01 default path) green.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>