fix(gitignore): ignore .ansible cache directory

A root-owned, empty .ansible/ (collections/modules/roles) directory
skeleton can appear in the repo root, from some root-run containerized
process's Ansible invocation resolving its collections_paths default
against the wrong $HOME. Confirmed this is not the project's own
convention: every reference in the codebase (Makefile, scripts/install/
all.sh, .github/workflows/lint-ansible.yml) consistently targets
~/.ansible/collections outside the repo, and .ansible/ has never been
tracked in this repository's history. Regardless of the exact trigger,
this directory is untracked and root-owned, and being previously
unlisted caused 'git stash push -u' to abort mid-cleanup on it
(EACCES), silently leaving other unrelated working-tree changes
unreset.

.dockerignore

@@ -40,6 +40,7 @@ compose/coredns/Corefile
 compose/Corefile
 
 # Host shell / editor / tooling state accidentally surfaced inside this working copy
+.ansible
 .bash_profile
 .bashrc
 .gitconfig

.gitignore

@@ -40,6 +40,7 @@ compose/coredns/Corefile
 compose/Corefile
 
 # Host shell / editor / tooling state accidentally surfaced inside this working copy
+.ansible
 .bash_profile
 .bashrc
 .gitconfig