chore(ansible): use project-local uv venv for ansible runtime deps

Moves the local ansible runtime from a global `uv tool install ansible-core`
(which required remembering `--with kubernetes --with jmespath --with dnspython`)
to a project-managed venv described by `pyproject.toml` + `uv.lock`. Fixes the
"Failed to import the required Python library (kubernetes)" error on localhost.

The localhost inventory entry now derives `ansible_python_interpreter` from
`{{ ansible_playbook_python }}`, so `uv run ansible-playbook` is enough — no
more hardcoded user-specific paths.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -1,4 +1,5 @@
 .terraform
 .terraform.*
 .DS_Store
-node_modules/
+node_modules/
+.venv/