ci: remove RIE terminal job and narrow RIE triggers (#507)

[James3014]

Closes #507.

Owner-approved 2026-10-13. The RIE terminal job almost always times out (reports green only via continue-on-error) and burns runner minutes and job slots.

• Deletes the terminal job from .github/workflows/repository-intelligence.yml.
• Drops labeled, unlabeled, edited, converted_to_draft triggers; keeps opened, synchronize, reopened, ready_for_review.
• snapshot is unchanged.
• Marks repository_intelligence_artifact snapshotKind=terminal as deprecated (tool still serves event artifacts and historical terminal ones). scripts/consume-rie-artifact.py left as is.
• NOTE: another session owns devspace main; do not merge from the removal session.

Tests: workflow YAML parses (jobs: snapshot; types as above); no workflow-structure test references the workflow.

🤖 Generated with Claude Code