Fix remaining ansible-lint violations: file permissions, var-naming, package pinning

- risky-file-permissions (32): add explicit mode: to copy/template/file tasks,
  matching the umask-derived permissions they already had (0644 for configs
  and systemd units, 0755 for created directories) — no functional change.
- var-naming (28): prefix role-scoped vars with their role name across
  pi_dhtsensor, pi_dhtsensor_circuitpython, pi_shairport, pi_squeezelite,
  pi_squeezelite_custom, pi_sispmctl, pi_standard_setup, and pi_sysdweb's
  sysdweb_name (shared by 9 consuming roles). Updated every dependent
  template, task reference, and matching inventory.yml override, and
  verified resolved values with ansible-inventory before/after.
- Fixes a latent bug found while renaming: pi_standard_setup's "Get/Change
  WiFi country" tasks reused the name wifi_country for both the role default
  and a register, so the register silently clobbered the default before
  do_wifi_country ever read it. Split into distinct names so the intended
  default value is used.
- package-latest (2): pin docker-ce/docker-compose-plugin installs in
  server_debian_docker to state: present.
- no-handler (1): move pi_lirc's "Reboot if boot overlay changed" into a
  proper handler notified by the boot-overlay task.

ansible-lint now passes clean at the production profile.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

roles/pi_sispmctl/tasks/main.yml

@@ -2,7 +2,7 @@
 - name: Check if sispmctl already exists
   ansible.builtin.stat:
     path: /usr/bin/sispmctl
-  register: sispmctl_file
+  register: pi_sispmctl_file
 - name: Install dependencies
   ansible.builtin.apt:
     name: "libusb-dev"
@@ -12,15 +12,16 @@
   ansible.builtin.unarchive:
     src: sispmctl-4.7.tar.gz
     dest: /tmp
-  when: not sispmctl_file.stat.exists
+  when: not pi_sispmctl_file.stat.exists
 - name: Build and install
   ansible.builtin.shell: cd /tmp/sispmctl*/ && ./configure --prefix=/usr && make install
-  when: not sispmctl_file.stat.exists
+  when: not pi_sispmctl_file.stat.exists
   changed_when: true
 - name: Install systemd service file
   ansible.builtin.copy:
     src: sispmctl.service
     dest: /lib/systemd/system/
+    mode: "0644"
 - name: Add script to autostart and start now
   ansible.builtin.systemd:
     name: sispmctl
@@ -31,4 +32,4 @@
   ansible.builtin.include_role:
     name: pi_sysdweb
   vars:
-    sysdweb_name: sispmctl
+    pi_sysdweb_name: sispmctl