Resolve conflicts from origin/main: relocate new CLI additions
(checkpoint_tui, deploy/validate, remote_template, content_crew
templates) into lib/cli, rewrite imports for the standalone
crewai-cli package, port main's trained_agents_file param and
predeploy validation, and bump python-dotenv/pydantic in
crewai-cli to match crewai's constraints. Add the new
mark_ephemeral_trace_batch_as_failed method to the relocated
crewai.plus_api. Update tests for the new payload field, deploy
--skip-validate kwarg, and crewai_cli import paths.
Move and adapt all CLI tests from lib/crewai/tests/cli/ to
lib/cli/tests/, updating import paths from crewai.cli.* to
crewai_cli.* and adjusting mock targets accordingly.
