feat: add session indicators and top exec commands to dashboard

Add visual indicators to session tables (replay badge when events exist,
exec badge for exec sessions) and a new "Top Exec Commands" table on the
dashboard. Includes EventCount field on Session, GetTopExecCommands on
Store interface, and truncateCommand template function.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/storage/sqlite_test.go

@@ -204,6 +204,79 @@ func TestDeleteRecordsBefore(t *testing.T) {
 	}
 }
 
+func TestGetTopExecCommands(t *testing.T) {
+	store := newTestStore(t)
+	ctx := context.Background()
+
+	// Create sessions with exec commands.
+	for range 3 {
+		id, err := store.CreateSession(ctx, "10.0.0.1", "root", "", "")
+		if err != nil {
+			t.Fatalf("creating session: %v", err)
+		}
+		if err := store.SetExecCommand(ctx, id, "uname -a"); err != nil {
+			t.Fatalf("setting exec command: %v", err)
+		}
+	}
+	for range 2 {
+		id, err := store.CreateSession(ctx, "10.0.0.2", "admin", "", "")
+		if err != nil {
+			t.Fatalf("creating session: %v", err)
+		}
+		if err := store.SetExecCommand(ctx, id, "cat /etc/passwd"); err != nil {
+			t.Fatalf("setting exec command: %v", err)
+		}
+	}
+	// Session without exec command — should not appear.
+	if _, err := store.CreateSession(ctx, "10.0.0.3", "test", "bash", ""); err != nil {
+		t.Fatalf("creating session: %v", err)
+	}
+
+	entries, err := store.GetTopExecCommands(ctx, 10)
+	if err != nil {
+		t.Fatalf("GetTopExecCommands: %v", err)
+	}
+	if len(entries) != 2 {
+		t.Fatalf("len = %d, want 2", len(entries))
+	}
+	if entries[0].Value != "uname -a" || entries[0].Count != 3 {
+		t.Errorf("entries[0] = %+v, want uname -a:3", entries[0])
+	}
+	if entries[1].Value != "cat /etc/passwd" || entries[1].Count != 2 {
+		t.Errorf("entries[1] = %+v, want cat /etc/passwd:2", entries[1])
+	}
+}
+
+func TestGetRecentSessionsEventCount(t *testing.T) {
+	store := newTestStore(t)
+	ctx := context.Background()
+
+	id, err := store.CreateSession(ctx, "10.0.0.1", "root", "bash", "")
+	if err != nil {
+		t.Fatalf("creating session: %v", err)
+	}
+
+	// Add some events.
+	events := []SessionEvent{
+		{SessionID: id, Timestamp: time.Now(), Direction: 0, Data: []byte("ls\n")},
+		{SessionID: id, Timestamp: time.Now(), Direction: 1, Data: []byte("file1\n")},
+	}
+	if err := store.AppendSessionEvents(ctx, events); err != nil {
+		t.Fatalf("appending events: %v", err)
+	}
+
+	sessions, err := store.GetRecentSessions(ctx, 10, false)
+	if err != nil {
+		t.Fatalf("GetRecentSessions: %v", err)
+	}
+	if len(sessions) != 1 {
+		t.Fatalf("len = %d, want 1", len(sessions))
+	}
+	if sessions[0].EventCount != 2 {
+		t.Errorf("EventCount = %d, want 2", sessions[0].EventCount)
+	}
+}
+
 func TestNewSQLiteStoreCreatesFile(t *testing.T) {
 	dbPath := filepath.Join(t.TempDir(), "test.db")
 	store, err := NewSQLiteStore(dbPath)