refactor(bootstrap): standardize patterns, extract common logic, remove dead code

- Make timezone, locale, and keymap configurable via system_cfg
- Consolidate rhel8/9/10.repo.j2 into single rhel.repo.j2 template
- Extract bootstrap_common_conditional for shared firewall/LUKS/guest packages
- Remove redundant version aliases (fedora40-43, debian10-13, rhel8-10, etc.)
- Simplify bootstrap dispatch from 10 conditional blocks to single mapping
- Merge bootstrap_ubuntu_lts into bootstrap_ubuntu (identical)
- Remove orphaned firstrun.sh.j2 template
- Remove configuration/defaults/main.yml aliases, inline into banner.yml
- Remove unnecessary changed_when: false on set_fact/debug tasks
- Deduplicate hostname variable computation in locales.yml
- Update README with timezone/locale/keymap variable reference

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

roles/bootstrap/tasks/rhel.yml

@@ -2,10 +2,8 @@
 - name: Bootstrap RHEL System
   block:
     - name: Install base packages in chroot environment
-      vars:
-        bootstrap_rhel_release: "{{ bootstrap_os_key | replace('rhel', '') }}"
       ansible.builtin.command: >-
-        dnf --releasever={{ bootstrap_rhel_release }} --repo={{ bootstrap_os_key }}-baseos
+        dnf --releasever={{ os_version_major }} --repo=rhel{{ os_version_major }}-baseos
         --installroot=/mnt
         --setopt=install_weak_deps=False --setopt=optional_metadata_types=filelists
         groupinstall -y core base standard
@@ -39,14 +37,13 @@
 
     - name: Copy RHEL repo file into chroot environment
       ansible.builtin.copy:
-        src: /etc/yum.repos.d/{{ bootstrap_os_key }}.repo
+        src: /etc/yum.repos.d/rhel.repo
         dest: /mnt/etc/yum.repos.d/redhat.repo
         mode: "0644"
         remote_src: true
 
     - name: Install additional packages in chroot
       vars:
-        bootstrap_rhel_release: "{{ bootstrap_os_key | replace('rhel', '') }}"
         bootstrap_rhel_extra: >-
           {{
             lookup('vars', bootstrap_var_key)
@@ -54,7 +51,7 @@
             | join(' ')
           }}
       ansible.builtin.command: >-
-        {{ chroot_command }} dnf --releasever={{ bootstrap_rhel_release }}
+        {{ chroot_command }} dnf --releasever={{ os_version_major }}
         --setopt=install_weak_deps=False install -y {{ bootstrap_rhel_extra }}
       register: bootstrap_result
       changed_when: bootstrap_result.rc == 0