feat(tui): add SLA reporting view

Full-screen SLA report accessible via [s] from detail panel.
Computes uptime%, downtime, outage count, longest outage, MTTR,
and MTBF from state_changes table. Includes daily breakdown with
bar chart, switchable time periods (24h/7d/30d/90d), and
scrollable viewport. LATE/STALE treated as UP for SLA purposes.

internal/store/sqlstore.go

@@ -370,6 +370,23 @@ func (s *SQLStore) GetStateChanges(siteID int, limit int) ([]models.StateChange,
 	return changes, rows.Err()
 }
 
+func (s *SQLStore) GetStateChangesSince(siteID int, since time.Time) ([]models.StateChange, error) {
+	rows, err := s.db.Query(s.q("SELECT id, site_id, from_status, to_status, error_reason, changed_at FROM state_changes WHERE site_id = ? AND changed_at >= ? ORDER BY changed_at DESC"), siteID, since)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var changes []models.StateChange
+	for rows.Next() {
+		var sc models.StateChange
+		if err := rows.Scan(&sc.ID, &sc.SiteID, &sc.FromStatus, &sc.ToStatus, &sc.ErrorReason, &sc.ChangedAt); err != nil {
+			return changes, err
+		}
+		changes = append(changes, sc)
+	}
+	return changes, rows.Err()
+}
+
 func (s *SQLStore) SaveCheck(siteID int, latencyNs int64, isUp bool) error {
 	return s.SaveCheckFromNode(siteID, "", latencyNs, isUp)
 }

internal/store/store.go

@@ -1,6 +1,8 @@
 package store
 
 import (
+	"time"
+
 	"gitea.lerkolabs.com/lerkolabs/uptop/internal/models"
 )
 
@@ -41,6 +43,7 @@ type Store interface {
 	// State Changes
 	SaveStateChange(siteID int, fromStatus, toStatus, errorReason string) error
 	GetStateChanges(siteID int, limit int) ([]models.StateChange, error)
+	GetStateChangesSince(siteID int, since time.Time) ([]models.StateChange, error)
 
 	// Nodes
 	RegisterNode(node models.ProbeNode) error