Refactor web health checker & domain expectations (filter-based)

- Move all domain→expected-status mapping to filter `web_health_expectations`.
- Require explicit app selection via non-empty `group_names`; only those apps are included.
- Add `www_enabled` flag (wired via `WWW_REDIRECT_ENABLED`) to generate/force www.* → 301.
- Support `redirect_maps` to include manual redirects (sources forced to 301), independent of app selection.
- Aliases always 301; canonicals use per-key override or `server.status_codes.default`, else [200,302,301].
- Remove legacy fallbacks (`server.status_codes.home` / `landingpage`).
- Wire filter output into systemd ExecStart script as JSON expectations.
- Normalize various templates to use `to_json` and minor spacing fixes.
- Update app configs (e.g., YOURLS default=301; Confluence default=302; Bluesky web=405; MediaWiki/Confluence canonical/aliases).
- Constructor now uses `WWW_REDIRECT_ENABLED` for domain generation.

Tests:
- Add comprehensive unit tests for filter: selection by group, keyed/default codes, aliases, www handling, redirect_maps, input sanitization.
- Add unit tests for the standalone checker script (JSON parsing, OK/mismatch counting, sanitization).

See conversation: https://chatgpt.com/share/68c2b93e-de58-800f-8c16-ea05755ba776

roles/web-app-keycloak/templates/import/components/org.keycloak.storage.UserStorageProvider.json.j2

@@ -245,7 +245,7 @@
 
     {# Build objectClasses from structural + auxiliary definitions #}
     "userObjectClasses": [
-      {{ KEYCLOAK_LDAP_USER_OBJECT_CLASSES | trim | tojson }}
+      {{ KEYCLOAK_LDAP_USER_OBJECT_CLASSES | trim | to_json }}
     ],
 
     "rdnLDAPAttribute": [ "{{ LDAP.USER.ATTRIBUTES.ID }}" ],

roles/web-app-keycloak/templates/import/components/org.keycloak.userprofile.UserProfileProvider.json.j2

@@ -55,7 +55,7 @@
     "providerId": "declarative-user-profile",
     "subComponents": {},
     "config": {
-      "kc.user.profile.config": [{{ (user_profile | tojson) | tojson }}]
+      "kc.user.profile.config": [{{ (user_profile | to_json) | to_json }}]
     }
   }
 ]