packaging: ship firewalld services on rpm + deb too, share from packaging/linux

Mirror the Arch firewalld service definitions into the RPM spec and the Debian
host package so every Linux packager installs them, and move the two XML files
to the shared packaging/linux/ home (alongside the .desktop files both the
PKGBUILD and deb scripts already source there) so there's one source of truth
instead of three drifting copies.

- rpm: install punktfunk-{gamestream,native}.xml to /usr/lib/firewalld/services/,
  list them in %files host, and print the firewalld enable command in %post
  (gated on firewall-cmd). Fedora/RHEL run firewalld by default, so this is where
  it matters most; Bazzite inherits it via the sysext built from the package /usr.
- deb: install both XMLs in build-deb.sh and add the same firewalld-gated hint to
  the postinst. Debian/Ubuntu ship no active firewall, so it's a no-op unless the
  admin runs firewalld.
- PKGBUILD + arch README updated to the packaging/linux/ path.
- Firewall docs (bazzite README now leads with --add-service; debian README gains
  a firewalld block) point at the shipped services; XML comments made
  distro-neutral. Never auto-enabled — packages don't touch the admin's firewall.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packaging/debian/build-deb.sh

@@ -80,6 +80,13 @@ install -Dm0644 scripts/host.env.example           "$SHAREDIR/host.env.example"
 install -Dm0644 packaging/bazzite/host.env         "$SHAREDIR/host.env.bazzite"
 install -Dm0644 packaging/kde/host.env             "$SHAREDIR/host.env.kde"
 install -Dm0644 api/openapi.json              "$SHAREDIR/openapi.json"
+# firewalld service definitions (shared across all Linux packaging). NOT auto-enabled — the postinst
+# only prints the enable command when firewalld is present. Debian/Ubuntu ship no active firewall
+# (Ubuntu's ufw is installed-but-inactive), so these are a no-op unless the admin runs firewalld.
+install -Dm0644 packaging/linux/punktfunk-gamestream.xml \
+                "$STAGE/usr/lib/firewalld/services/punktfunk-gamestream.xml"
+install -Dm0644 packaging/linux/punktfunk-native.xml \
+                "$STAGE/usr/lib/firewalld/services/punktfunk-native.xml"
 install -Dm0644 LICENSE-MIT                         "$DOCDIR/LICENSE-MIT"
 install -Dm0644 LICENSE-APACHE                      "$DOCDIR/LICENSE-APACHE"
 install -Dm0644 README.md                           "$DOCDIR/README.md"
@@ -186,6 +193,12 @@ if [ "$1" = "configure" ]; then
     echo "    sudo usermod -aG input \"\$USER\"   # then re-login"
     echo "Config:  mkdir -p ~/.config/punktfunk && cp /usr/share/punktfunk-host/host.env.example ~/.config/punktfunk/host.env"
     echo "Enable:  systemctl --user enable --now punktfunk-host"
+    # Debian/Ubuntu ship no active firewall; only hint firewalld users (ufw users: see README).
+    if command -v firewall-cmd >/dev/null 2>&1; then
+        echo "Firewall (firewalld detected): sudo firewall-cmd --reload &&"
+        echo "    sudo firewall-cmd --permanent --add-service=punktfunk-gamestream && sudo firewall-cmd --reload"
+        echo "    (use punktfunk-native for the native-only host)"
+    fi
 fi
 exit 0
 EOF