Use dynamic cloudflare trusted_proxies IP source

caddy-cf now includes WeidiDeng/caddy-cloudflare-ip, so replace the
hardcoded 22-range static list with 'trusted_proxies cloudflare' which
auto-fetches and refreshes Cloudflare's IPv4/IPv6 ranges (interval 12h,
timeout 15s). No static list to keep in sync when Cloudflare updates.

Kept client_ip_headers Cf-Connecting-Ip X-Forwarded-For (prefer CF's
authoritative end-user IP, fall back to XFF) and documented why.

Validated + fmt-clean and tested end-to-end against the updated caddy-cf
image: starts cleanly, serves HTTP 200 with gzip + security headers.

Caddyfile

@@ -15,34 +15,19 @@
 	# X-Forwarded-For) are honoured only when the request actually comes from
 	# Cloudflare. This prevents header spoofing from any other source.
 	#
-	# Ranges from https://www.cloudflare.com/ips-v4/ and /ips-v6/ .
-	# Keep in sync when Cloudflare updates them (rarely). If you rebuild
-	# caddy-cf with the caddy-dynamic-cloudflare / caddy-cloudflare-ip plugin,
-	# this static list can be replaced with `trusted_proxies cloudflare`.
+	# The `cloudflare` IP source (WeidiDeng/caddy-cloudflare-ip, baked into the
+	# caddy-cf image) auto-fetches the ranges from cloudflare.com/ips-v4 and
+	# /ips-v6 and refreshes them periodically, so there's no static list to
+	# keep in sync.
 	servers {
-		trusted_proxies static \
- 173.245.48.0/20 \
- 103.21.244.0/22 \
- 103.22.200.0/22 \
- 103.31.4.0/22 \
- 141.101.64.0/18 \
- 108.162.192.0/18 \
- 190.93.240.0/20 \
- 188.114.96.0/20 \
- 197.234.240.0/22 \
- 198.41.128.0/17 \
- 162.158.0.0/15 \
- 104.16.0.0/13 \
- 104.24.0.0/14 \
- 172.64.0.0/13 \
- 131.0.72.0/22 \
- 2400:cb00::/32 \
- 2606:4700::/32 \
- 2803:f800::/32 \
- 2405:b500::/32 \
- 2405:8100::/32 \
- 2a06:98c0::/29 \
- 2c0f:f248::/32
+		trusted_proxies cloudflare {
+			interval 12h
+			timeout 15s
+		}
+		# Read the real visitor IP from these headers (only honoured for
+		# requests from trusted_proxies above). Cf-Connecting-Ip is
+		# Cloudflare's single authoritative end-user IP; X-Forwarded-For is
+		# the fallback if a request ever arrives without the CF header.
 		client_ip_headers Cf-Connecting-Ip X-Forwarded-For
 	}
 }