fix: don't count same-account solves toward MIN_VALID_SOLVED_ISSUES gate

[hunnyboy1217]

Summary

Moves the same-account (discoverer == solver) check ahead of the valid_solved_count increment in _score_miner_mirror_issues so self-filed-and-self-solved issues no longer count toward the MIN_VALID_SOLVED_ISSUES = 7 eligibility gate. Previously the counter incremented at mirror_scan.py:328-329 before the same-account continue at line 332, letting a miner satisfy the gate with self-loops despite the module docstring listing "anti-self-issue" as an applied anti-gaming gate (mirror_scan.py:19).

After this PR: same-account solves still bump total_solved_issues (credibility) but do not bump total_valid_solved_issues, so they cannot satisfy the discovery eligibility gate.

Related Issues

Fixes #1255

Type of Change

• Bug fix
• New feature
• Refactor
• Documentation
• Other (describe below)

Testing

• Tests added/updated
• Manually tested

Extended test_self_issue_counts_credibility_but_no_score in tests/validator/issue_discovery/test_mirror_scan.py with assert eval_.total_valid_solved_issues == 0 to lock in the gate-bypass fix.

Test runs:

pytest tests/validator/issue_discovery/test_mirror_scan.py
42 passed in 0.22s

pytest tests/validator/test_issue_eligibility.py tests/validator/issue_discovery/
46 passed in 0.17s

Checklist

• Code follows project style guidelines
• Self-review completed
• Changes are documented (if applicable)

Notes for reviewers

• Single-function change, no protocol or abstraction changes, matches scope described in [Bug] valid_solved_count increments on same-account solves, bypassing MIN_VALID_SOLVED_ISSUES eligibility gate #1255.
• Added a short comment at the reordered check pointing back to the module docstring so the ordering can't silently regress.
• The other "credibility only" branches (one-issue-per-PR siblings, sub-threshold solving PRs) intentionally still fall after the increment — they're not affected by this fix and a sub-threshold solving PR can't increment valid_solved_count anyway since the increment is gated on the same MIN_TOKEN_SCORE_FOR_BASE_SCORE threshold.