Implement reserved username handling for users, LDAP and Keycloak

Add end-to-end support for reserved usernames and tighten CAPTCHA / Keycloak logic.

Changes:

- Makefile: rename EXTRA_USERS → RESERVED_USERNAMES and pass it as --reserved-usernames to the users defaults generator.

- cli/build/defaults/users.py: propagate  flag into generated users, add --reserved-usernames CLI option and mark listed accounts as reserved.

- Add reserved_users filter plugin with  and  helpers for Ansible templates and tasks.

- Add unit tests for reserved_users filters and the new reserved-usernames behaviour in the users defaults generator.

- group_vars/all/00_general.yml: harden RECAPTCHA_ENABLED / HCAPTCHA_ENABLED checks with default('') and explicit > 0 length checks.

- svc-db-openldap: introduce OPENLDAP_PROVISION_* flags, add OPENLDAP_PROVISION_RESERVED and OPERNLDAP_USERS to optionally exclude reserved users from provisioning.

- svc-db-openldap templates/tasks: switch role/group LDIF and user import loops to use OPERNLDAP_USERS instead of the full users dict.

- networks: assign dedicated subnet for web-app-roulette-wheel.

- web-app-keycloak vars: compute KEYCLOAK_RESERVED_USERNAMES_LIST and KEYCLOAK_RESERVED_USERNAMES_REGEX from users | reserved_usernames.

- web-app-keycloak user profile template: inject reserved-username regex into username validation pattern and improve error message, fix SSH public key attribute usage and add component name field.

- web-app-keycloak update/_update.yml: strip subComponents from component payloads before update and disable async/poll for easier debugging.

- web-app-keycloak tasks/main.yml: guard cleanup include with MODE_CLEANUP and keep reCAPTCHA update behind KEYCLOAK_RECAPTCHA_ENABLED.

- user/users defaults: mark system/service accounts (root, daemon, mail, admin, webmaster, etc.) as reserved so they cannot be chosen as login names.

- svc-prx-openresty vars: simplify OPENRESTY_CONTAINER lookup by dropping unused default parameter.

- sys-ctl-rpr-btrfs-balancer: simplify main.yml by removing the extra block wrapper.

- sys-daemon handlers: quote handler name for consistency.

Context: change set discussed and refined in ChatGPT on 2025-11-29 (Infinito.Nexus reserved usernames & Keycloak user profile flow). See conversation: https://chatgpt.com/share/692b21f5-5d98-800f-8e15-1ded49deddc9

cli/build/defaults/users.py

@@ -70,6 +70,7 @@ def build_users(defs, primary_domain, start_id, become_pwd):
         description = overrides.get('description')
         roles = overrides.get('roles', [])
         password = overrides.get('password', become_pwd)
+        reserved = overrides.get('reserved', False) 
 
         # Determine UID and GID
         if 'uid' in overrides:
@@ -89,6 +90,9 @@ def build_users(defs, primary_domain, start_id, become_pwd):
         if description is not None:
             entry['description'] = description
 
+        if reserved:
+            entry['reserved'] = reserved
+
         users[key] = entry
 
     # Ensure uniqueness of usernames and emails
@@ -180,8 +184,8 @@ def parse_args():
         help='Starting UID/GID number (default: 1001).'
     )
     parser.add_argument(
-        '--extra-users', '-e',
-        help='Comma-separated list of additional usernames to include.',
+        '--reserved-usernames', '-e',
+        help='Comma-separated list of usernames to reserve.',
         default=None
     )
     return parser.parse_args()
@@ -198,17 +202,21 @@ def main():
         print(f"Error merging user definitions: {e}", file=sys.stderr)
         sys.exit(1)
 
-    # Add extra users if specified
-    if args.extra_users:
-        for name in args.extra_users.split(','):
+    # Add reserved/ users if specified
+    if args.reserved_usernames:
+        for name in args.reserved_usernames.split(','):
             user_key = name.strip()
             if not user_key:
                 continue
             if user_key in definitions:
-                print(f"Warning: extra user '{user_key}' already defined; skipping.", file=sys.stderr)
+                print(
+                    f"Warning: reserved user '{user_key}' already defined; skipping (not changing existing definition).",
+                    file=sys.stderr
+                )
             else:
                 definitions[user_key] = {}
-
+            # Mark user as reserved
+            definitions[user_key]["reserved"] = True
     try:
         users = build_users(
             definitions,