Keep the media-pi roles working on trixie

- pi_hifiberry_amp: the boot config lives at /boot/firmware/config.txt.
- pi_sysdweb: install python3-dbus and python3-systemd from apt, which trixie ships at
  the versions sysdweb needs; bookworm gets the headers pip needs to build dbus-python
  1.4 itself.
- pi_squeezeserver: trixie images have no iptables, and so cannot have the port 80
  redirect that absent.yml removes - skip that step there instead of failing.
- pi_modern_shell_env, pi_slint_frontend: read facts through `ansible_facts` rather than
  the deprecated injected `ansible_*` variables.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

roles/pi_sysdweb/tasks/main.yml

@@ -4,6 +4,18 @@
     name: python3-pip
     cache_valid_time: 7200
     state: present
+- name: Apt install sysdweb's dbus and systemd dependencies
+  # sysdweb needs dbus-python ~= 1.4, which PyPI only ships as source (meson build needing
+  # pkg-config and the dbus/glib headers), and systemd-python, which needs libsystemd-dev.
+  # Trixie packages both (python3-dbus is exactly 1.4, python3-systemd 235), and pip counts
+  # the apt versions as satisfied. Bookworm has dbus 1.3, so there pip has to build 1.4.
+  ansible.builtin.apt:
+    name: >-
+      {{ ['python3-dbus', 'python3-systemd']
+         + (['build-essential', 'pkg-config', 'python3-dev', 'libdbus-1-dev', 'libglib2.0-dev', 'libsystemd-dev']
+            if ansible_facts.distribution_major_version | int < 13 else []) }}
+    cache_valid_time: 7200
+    state: present
 - name: Install sysdweb
   ansible.builtin.pip:
     name: sysdweb