Persist nonrecoverable miner invalidation

[wang-tong0]

Summary

• Persist nonrecoverable miner invalidation reasons on miner_stats so later monitor refreshes cannot silently restore the same (hotkey, revision) to valid.
• Restrict automatic invalid-to-valid recovery to no_commit and transient infrastructure failures such as HF fetch/tokenizer/template fetch errors.
• Treat deterministic HF/model problems, plagiarism, anticopy copy verdicts, model checks, revision mismatches, and gated/private/not-found repos as nonrecoverable for the current revision.

Root Cause

miners.is_valid is rewritten by every monitor refresh. Some miner-attributable invalid states were only represented in the current UID-keyed miners row, so a later refresh could overwrite them with is_valid=true once the immediate detection condition disappeared.

Validation

python -m py_compile affine/src/monitor/miners_monitor.py affine/database/dao/miner_stats.py
python -m pytest tests/test_dao_adapters.py tests/test_anticopy_monitor_step8.py tests/test_miners_monitor_gated.py tests/test_challenger_queue.py -q
git diff --check

Result: 41 passed.