docs: add wait-for-checks CLI command, ADR-0002, update architecture docs

Phase 1e-f of REFACTORING-PLAN.md:

- Register `devx ci wait-for-checks` in cli.py with test coverage
- Add ADR-0002 documenting the ansible_checks consolidation and
  wait_for_checks extraction decisions
- Update AGENTS.md package structure to reflect ansible_checks/
  subpackage and deprecated ci/discover_runners wrapper
- Update docs/user/cli-commands.md with wait-for-checks documentation
  and discover-runners deprecation notice
- Update docs/tech/architecture.md with new modules and canonical
  discover_runners location
- Update docs/mapping.json with ADR entries

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

tests/unit/test_cli.py

@@ -150,6 +150,13 @@ class TestCiCommands:
         assert result.exit_code == 0
         mock_run.assert_called_once_with("devx.ci.validate_commit_msg", ["msg"])
 
+    @patch("devx.cli._run_module")
+    def test_ci_wait_for_checks(self, mock_run: MagicMock) -> None:
+        runner = CliRunner()
+        result = runner.invoke(cli, ["ci", "wait-for-checks", "--", "--job-name", "molecule-tests"])
+        assert result.exit_code == 0
+        mock_run.assert_called_once_with("devx.ci.wait_for_checks", ["--job-name", "molecule-tests"])
+
 
 class TestToolsCommands:
     @patch("devx.cli._run_module")