Accelerate Reference Spine Overview Lists

1. Runtime

• Add a Postgres recent-event first-page path for unfiltered spine overview lists.
• Keep filtered/cursor list reads on the existing aggregate path.
• Hydrate selected page summaries with bounded concurrency.
• Add Postgres recent-correlation indexes to schema bootstrap and migration.
• Remove unused failed-run/failed-trace reads from the dashboard home.

2. Tests

• Add regression coverage for unfiltered recent first-page spine lists.
• Add regression coverage that filtered/cursor reads do not use the recent fast path.
• Run reference and console type checks.
• Run OpenSpec strict/all.

3. Live Verification

• Create the recent-correlation indexes on live Postgres or verify bootstrap created them.
• Verify /_ref/traces?limit=6 and /_ref/runs?limit=100 before/after latency.
• Verify /dashboard and /dashboard/runs with the browser harness.