fix(ten-427): fall back to PR branch/title for TEN issue matching

[marvin-tensorleap]

Why this change exists

When an agent opens a PR without backfilling the GitHub ref (e.g. tensorleap/paperclip#15) into the issue description, findTenIssue's text search finds nothing and creates a spurious triage issue (like TEN-425) instead of waking the real assignee. This happened on Assaf's review of PR #15, which belongs to TEN-334 — the dispatcher couldn't connect the two and opened a triage issue.

Tracked in TEN-427. Follow-up to #15.

How this PR fixes it

Two new functions are added in worker.ts:

• extractTenIdentifierFromPR(payload) — scans the PR's head.ref (branch name) and then title for the pattern /\bten[_-](\d+)\b/i and returns the canonical TEN-NNN string. Branch is checked first because it's more structured.
• findTenIssueByIdentifier(ctx, companyId, identifier) — queries the issues API with the identifier as q, then filters for an exact identifier match (case-insensitive) so broad text-search tokenization can't produce false positives.

In onWebhook, after the primary findTenIssue full-text search returns null, the fallback fires: extract TEN identifier → look up by identifier → dispatch if found. The triage path is unchanged and still runs when the fallback also misses.

Technical summary

• packages/plugins/examples/plugin-github-webhook-dispatcher/src/worker.ts
  • Added extractTenIdentifierFromPR (pure function, no async)
  • Added findTenIssueByIdentifier (async, one issues.list call)
  • Added fallback block in onWebhook between primary search and triage creation
• tests/plugin.spec.ts
  • Added 3 new tests in PR branch/title fallback describe block

Verification

✓ tests/plugin.spec.ts (22 tests) 15ms
Test Files  1 passed (1)
     Tests  22 passed (22)

New tests:

1. pull_request_review.submitted for a PR with branch ten-334-exact-match-issue-finder dispatches to TEN-334 (no ref in description)
2. pull_request.opened with title fix(ten-334): … and non-matching branch dispatches to TEN-334
3. PR with branch chore/update-deps and title chore: update deps (no TEN id) still creates triage issue