refactor(web): remove deprecated dashboard components and enhance KPI grid

- Deleted unused components: `DashboardActivityTimeline`, `DashboardFramePanel`, `DashboardModulesGrid`, `DashboardRecentJobsGrid`, and `DashboardRecentRevisionsGrid` to streamline the dashboard.
- Updated `DashboardKpiGrid` to improve KPI display logic, including progress indicators and enhanced badge functionality.
- Refactored `DashboardNetworkHealth` to provide better status representation based on loading states and network conditions.
- Introduced new properties for KPI cards to support progress tracking and improved visual feedback.

This cleanup aims to enhance performance and maintainability of the dashboard while providing a better user experience.

internal/repository/asn_cache.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"sync"
 	"time"
 
 	"evobgp/internal/store"
@@ -11,13 +12,26 @@ import (
 	"github.com/jackc/pgx/v5"
 )
 
+// asnCacheRowExistsOnce caches the schema check for the process lifetime (see moduleSnapshotRowTableExists).
+var (
+	asnCacheRowExistsOnce   sync.Once
+	asnCacheRowExistsCached bool
+)
+
 func asnCacheRowTableExists(ctx context.Context, q queryRower) bool {
-	var n int
-	err := q.QueryRow(ctx, `
-		SELECT 1 FROM information_schema.tables
-		WHERE table_schema = 'public' AND table_name = 'asn_prefix_cache_row'
-		LIMIT 1`).Scan(&n)
-	return err == nil
+	asnCacheRowExistsOnce.Do(func() {
+		var n int
+		err := q.QueryRow(ctx, `
+			SELECT 1 FROM information_schema.tables
+			WHERE table_schema = 'public' AND table_name = 'asn_prefix_cache_row'
+			LIMIT 1`).Scan(&n)
+		if err != nil {
+			asnCacheRowExistsOnce = sync.Once{}
+			return
+		}
+		asnCacheRowExistsCached = true
+	})
+	return asnCacheRowExistsCached
 }
 
 func (p *Postgres) GetASNPrefixCache(asn int64) (*store.ASNPrefixCacheEntry, bool, error) {