fix(packaging): open mgmt/library port 47990 on the LAN firewall profiles

The mgmt REST API has bound 0.0.0.0:47990 by default since ae51276 so paired
clients can browse the game library over mTLS, but every packaged firewall
opener still excluded 47990 and the docs still claimed it was loopback-only.
On any host with an active firewall (ufw/firewalld) the LAN game-library
feature was silently broken.

Add 47990/tcp to the native firewall profiles (punktfunk.ufw [punktfunk-native]
+ punktfunk-native.xml) and correct the stale "loopback-only by default" text
across the debian/arch/bazzite READMEs and the docs site (incl. the factually
wrong --mgmt-bind default in host-cli.md, 127.0.0.1 -> 0.0.0.0). Opening the
port adds no admin exposure: off-loopback mgmt::require_auth serves only the
read-only status/library allowlist to a paired client cert; the bearer-token
admin surface stays loopback-only regardless of the bind.

Windows was already sound (shared parse_serve binds 0.0.0.0; service.rs already
firewall-opens 47990) — add a clarifying comment so the rule isn't mistaken for
accidental over-exposure.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

packaging/linux/punktfunk.ufw

@@ -21,17 +21,22 @@
 
 [punktfunk-native]
 title=punktfunk host (native punktfunk/1)
-description=punktfunk/1 native streaming: QUIC control plane + mDNS auto-discovery
-ports=9777/udp|5353/udp
+description=punktfunk/1 native streaming: QUIC control plane + mDNS auto-discovery + mgmt/library API (HTTPS + mTLS)
+ports=9777/udp|5353/udp|47990/tcp
 
 [punktfunk-gamestream]
 title=punktfunk host (GameStream/Moonlight)
 description=GameStream/Moonlight compatibility ports (opt-in, trusted LAN only)
 ports=47984,47989,48010/tcp|47998:48010/udp|5353/udp
 
+# The mgmt REST API (TCP 47990, in the punktfunk-native profile above) binds all interfaces by
+# default so paired clients can browse the game library over mTLS. Off-loopback it exposes ONLY the
+# read-only status + library endpoints, and only to a paired client certificate; every admin action
+# (arming pairing, removing devices, session control, library edits) is honored over loopback only.
+# Run the host with `--mgmt-bind 127.0.0.1:47990` to keep 47990 loopback-only (then don't open it).
+#
 # The optional web console (the separate punktfunk-web package). Open only if you installed it and
 # want to reach it from another device — it binds all interfaces on TCP 47992 (HTTPS, login-gated).
-# The mgmt API (47990) is loopback-only and is deliberately not covered here.
 [punktfunk-web]
 title=punktfunk web console
 description=The optional punktfunk management web console (HTTPS, login-gated) reachable from the LAN