Romule 0.3.1 — behind a reverse proxy

A follow-up to 0.3.0: the reverse-proxy example the documentation kept
promising, and the four defects that writing it uncovered.

Added

• exemples/caddy/ — a complete reverse-proxy stack, with Romule not
  published on the host: it is reachable only through Caddy. CI stands the
  stack up on every change and replays the matrix that matters:

  	with ROMULE_TRUSTED_PROXIES	without
  a genuinely local client, through the proxy	200	403
  an outside client forging X-Forwarded-For: 127.0.0.1	403	403

  The two rows differ by one header and give opposite results. This cannot be
  proven with a double: what is being checked is what a real Caddy writes
  into the chain, and a double would only prove what it wrote itself.

• ROMULE_TRUSTED_PROXIES accepts CIDR — 172.16.0.0/12 beside
  127.0.0.1. Exact-string matching was fine while you wrote 127.0.0.1; it
  stopped being fine the moment there was a container, because Docker assigns
  the proxy's address dynamically. The setting the documentation recommends was
  impractical in the deployment it recommends: you had to read an address after
  every docker compose up and fix it when it changed.

Fixed

• A network notation was compared as an address. With
  ROMULE_TRUSTED_PROXIES=10.0.0.0/8, the literal string 10.0.0.0/8 was in
  the exact-match set, so a chain link equal to it counted as a declared relay.
  No exploitation is claimed — behind a real proxy the attacker's address is
  appended on the right and the walk stops there — but a notation is not an
  address, and it is fixed as the comparison bug it is.

• The startup banner said "Network: disabled" right above the address to
  connect to. The line followed the lan_access setting; in a container
  Romule listens on 0.0.0.0 and protects itself with a token, so the two
  disagreed in the most common case. It follows the socket now.

• The update notice no longer reads "Version v0.3.0 available". GitHub
  names its tags v0.3.0 and the interface already writes the word Version
  in front. The prefix is stripped for display only — the comparison never read
  it. Noticed by running the notifier against the first real release.

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Docker — docker pull ghcr.io/romule-app/romule:0.3.1 (also 0.3 and latest, amd64 and arm64)

Documentation — https://romule-app.github.io/romule/ · en français

Upgrading — docker compose pull && docker compose up -d. Your state lives in the /data volume and survives.