fix: repair 5 MCP analysis tools with SQL errors + seed entity_status rows

- get_event_timeline: event_type/actor/message → type/source/data::text
- get_blast_radius: add JOIN entities for slug column
- get_state_snapshot: remove nonexistent disk_usage_pct, drift_count
- get_change_history: timestamp/actor_label/details → ts/actor_id::text/detail
- seed: upsert entity_status rows during inventory ingest (was empty, causing INNER JOIN on get_health_summary to return nothing)

internal/db/seed.go

@@ -131,6 +131,18 @@ func IngestInventorySeed(ctx context.Context, tx pgx.Tx, data map[string]any) (*
 		if err != nil {
 			return nil, fmt.Errorf("entity %s: %w", slug, err)
 		}
+
+		// Seed initial entity_status row so health queries return
+		// results even before the scheduler populates check results.
+		_, err = tx.Exec(ctx,
+			`INSERT INTO entity_status (entity_id, health, updated_at)
+			 VALUES ($1, 'unknown', now())
+			 ON CONFLICT (entity_id) DO NOTHING`,
+			entityID)
+		if err != nil {
+			return nil, fmt.Errorf("entity_status %s: %w", slug, err)
+		}
+
 		r.Entities++
 	}