Tunnels now get a per-tunnel certificate from the configured ACME CA
(Let's Encrypt by default) with DNS-01 through Porkbun, keeping the
client's CSR and key. Issuance is asynchronous (issuing/ready/failed);
the account persists in the store, renewals run in a 30-day window with
retries, and a failed renewal keeps the old certificate serving.
Switching from the local CA reissues existing tunnels automatically,
and the admin dashboard shows the issuer and certificate state.
Verified against Pebble and Let's Encrypt staging.
The bare 'tunneld' ignore pattern also matched the cmd/tunneld
directory, so the server's main.go was never committed and the
Coolify build failed on COPY cmd. Also update deploy docs for the
Coolify/Traefik topology (API via HTTPS router, tunnel traffic via
TCP SNI passthrough).