feat(scoring): add draft-PR awareness to classification and queue health

[oktofeesh1]

Summary

• isDraftPullRequest() in src/scoring/pending-pr-scenarios.ts now checks pr.isDraft first, before falling through to title-pattern and label matching. Every other draft-detection site in the codebase (local-branch.ts:625, engine.ts:3968, commands.ts:1299, agent-sweep.ts:41, processors.ts:837) uses pr.isDraft directly; this function was the only outlier, silently misclassifying GitHub-native draft PRs as blocked when they lacked a draft title or label.
• buildQueueHealth() gains a new draftPullRequests signal (count of open draft PRs) and surfaces an inactive_draft_prs finding when any draft PR has gone 14+ days without an update — letting maintainers distinguish genuinely abandoned drafts from stale reviewable work without changing the existing stalePullRequests accounting.

Scope

• Changes are scoped to src/ and test/
• No migration, OpenAPI, or cf-typegen changes required
• No secrets, trust scores, wallet addresses, or reward values introduced
• site/, CNAME, and **/lovable/** untouched

Validation

• npm run test:ci fully green (3705 tests pass, 217 test files)
• git diff --check clean

Safety

• No auth, session, or CORS paths changed
• No public PR comment surface changed (queue health is maintainer-facing only)
• isDraftPullRequest() change is additive — existing title-pattern and label checks are preserved as fallback

[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.69%. Comparing base (9dfe6ad) to head (e6fee56).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1189   +/-   ##
=======================================
  Coverage   94.68%   94.69%           
=======================================
  Files         157      157           
  Lines       19074    19079    +5     
  Branches     6905     6907    +2     
=======================================
+ Hits        18061    18066    +5     
  Misses        424      424           
  Partials      589      589           

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