fix: return non-zero when PAT broadcast or check fails everywhere

[reganbuilds]

Summary

• return exit code 1 from gitt miner post when zero validators accept the PAT
• return exit code 1 from gitt miner check when zero validators report a valid PAT
• add focused CLI tests for both failure paths

Fixes #542.

Validation

• exercised both CLI paths through Click runner with mocked bittensor and synapse dependencies
• ran python3 -m py_compile gittensor/cli/miner_commands/post.py gittensor/cli/miner_commands/check.py tests/cli/test_miner_commands.py