refactor(healthcheck): support multiple profiles per host with aggregate result

Replace the single healthcheck_profile with a healthcheck_profiles list so a
host can run several checks (e.g. hk2: pdns, rustdesk, hk2aux). Profiles emit
per-check JSON to latest-<check>.json; the dispatcher clears stale per-check
files, runs every profile, and merges them into latest.json.

Contract: a single complete check keeps the historical verbatim latest.json
shape; several checks produce a worst-status aggregate retaining every check's
detail. A profile that crashes before reporting is aggregated as unknown so
latest.json can never go stale while the dispatcher fails. The dispatcher exits
with the worst (max) profile exit code.

ansible/roles/healthcheck/tasks/main.yml

@@ -1,9 +1,10 @@
 ---
-- name: Validate known health-check profile
+- name: Validate known health-check profiles
   ansible.builtin.assert:
     that:
-      - healthcheck_profile in healthcheck_profiles
-    fail_msg: "Unsupported healthcheck_profile: {{ healthcheck_profile }}"
+      - item in healthcheck_profile_scripts
+    fail_msg: "Unsupported healthcheck_profile: {{ item }}"
+  loop: "{{ healthcheck_profiles }}"
 
 - name: Install health-check directories
   ansible.builtin.file:
@@ -28,13 +29,14 @@
     group: root
     mode: "0755"
 
-- name: Install service health-check script
+- name: Install service health-check scripts
   ansible.builtin.template:
-    src: "{{ healthcheck_profiles[healthcheck_profile] }}.j2"
-    dest: "{{ healthcheck_install_root }}/{{ healthcheck_profiles[healthcheck_profile] }}"
+    src: "{{ healthcheck_profile_scripts[item] }}.j2"
+    dest: "{{ healthcheck_install_root }}/{{ healthcheck_profile_scripts[item] }}"
     owner: root
     group: root
     mode: "0755"
+  loop: "{{ healthcheck_profiles }}"
 
 - name: Install health-check dispatcher
   ansible.builtin.template: