refactor(bootstrap,configuration,environment): add defaults/main.yml and extract hardcoded values

roles/bootstrap/defaults/main.yml

@@ -0,0 +1,15 @@
+---
+# OS → task file mapping for bootstrap dispatch.
+# Each key matches a supported `os` value; value is the task file to include.
+bootstrap_os_task_map:
+  almalinux: _dnf_family.yml
+  alpine: alpine.yml
+  archlinux: archlinux.yml
+  debian: debian.yml
+  fedora: _dnf_family.yml
+  opensuse: opensuse.yml
+  rocky: _dnf_family.yml
+  rhel: rhel.yml
+  ubuntu: ubuntu.yml
+  ubuntu-lts: ubuntu.yml
+  void: void.yml