Moves the completed change to openspec/changes/archive/ and creates the canonical openspec/specs/observability/spec.md.
Co-authored-by: Cursor <cursoragent@cursor.com>
Spans are now created and exported to Sentry only when SENTRY_TRACING is enabled (default off), keeping 24/7 operation within the free-tier span quota. Error monitoring stays always-on. Includes OpenSpec change gate-sentry-spans (proposal, design, specs, tasks).
Co-authored-by: Cursor <cursoragent@cursor.com>