fix: report workflow errors that end at pause gates

[eshulman2]

Summary

Workflow failures could become invisible when graph routing ended at a pause gate. The worker suppressed all paused results, even when the invocation had produced a new last_error. Bug triage and task-takeover triage also returned triage_check for retryable failures, but their graph routers omitted that destination and silently fell through to triage_gate.

Changes

• Report a newly produced last_error even when the final workflow state is paused
• Continue deduplicating errors carried over from a previous invocation
• Route retryable task-takeover triage failures back to triage_check
• Route retryable bug triage failures back to triage_check
• Add regression coverage for paused errors and both triage graphs

The shared reporting fix also covers PRD, spec, epic, and task publishing errors that produce a new error before reaching an approval gate.

Validation

• Ruff passes for all changed source and test files
• 292 affected worker, graph, and flow tests pass

Context

Discovered while running AISOS-2157: a Vertex configuration failure ended at triage_gate with last_error, but no Jira error comment was posted.