feat: verify bounty claims when comments arrive

[Aming9303]

Summary

• run the configured verifier when a new claim or evidence comment arrives
• route comment events to only the matching bounty verifier while keeping the six-hour reconciliation sweep
• fail article verification closed unless the page has at least 300 words and a RustChain topic marker
• preserve idempotent reports and cover same-user/same-URL deduplication and zero-star claims

Why

The existing scheduled workflow can leave new claims waiting for up to six hours and runs unrelated verification phases. Event-targeted execution reacts promptly without launching the full stargazer sweep for non-star bounties.

Tests

• python -m unittest tests.test_verify_bounties tests.test_verify_bounties_distribution tests.test_verify_bounties_incomplete_sweep (36 passed)
• workflow YAML parsed with PyYAML

Refs #747

RTC wallet: RTCc8cdaa67b90f9b06987135b8b65ab037bfb603a9

[github-actions]

guard-bounty-pr: this PR is from a first-time/non-collaborator contributor (Aming9303) and touches automation or payout-critical paths:

• .github/workflows/verify-bounties.yml
• scripts/verify_bounties.py

Bounty/onboarding submissions are normally expected to add their own content (docs, a submissions/ entry, a small standalone script, etc.), not modify existing CI workflows, .github/scripts/, scripts/, or the bounty ledger/registry files. This is exactly the pattern seen in #14981, where a "solution" PR replaced working automation scripts with stubs.

This is not an automatic rejection -- a maintainer needs to look at the diff before this merges. If the changes to these paths are legitimate and intentional, a maintainer can dismiss this and merge normally.

[Aming9303]

The protected-path changes are intentional for the remaining #747 scope: the existing verifier and scheduled workflow live in these two files, and the missing work is the actual issue-comment event wiring. The PR preserves the scheduled reconciliation path, limits event runs to the configured issue verifier, and adds focused fail-closed tests (36 passing). Please apply the required maintainer review/tier rather than bypassing the guard.

[Scottcjn]

@Aming9303 CI is red on this one. Fix the failing job and ping me; the idea (run the matching verifier when a claim comment arrives, keep the 6-hour sweep, fail article checks closed under 300 words) is wanted and will get a real review once green. — Sophia

[Aming9303]

I checked the failed job and current branch again. The only red check is guard-bounty-pr: it deliberately exits non-zero whenever a non-collaborator changes .github/workflows/ or scripts/, and it has no contributor-side approval path. Those two protected files are required for the issue-comment event wiring you confirmed; removing them would remove the requested behavior. The focused verifier suite is 36/36 passing, the workflow parses, and the other available checks pass. Please perform the protected-path review and merge past/dismiss that guard, or point me to a maintainer-approved non-protected location if you want the implementation moved.