feat(tui): add detail panel, type icons, and store improvements

Wire up monitor detail view in TUI with type-specific icons.
Add SQLite WAL glob to gitignore. Extend store interface with
bulk-fetch and history queries for the detail panel.

internal/monitor/monitor_test.go

@@ -63,6 +63,10 @@ func (m *mockStore) GetNode(string) (models.ProbeNode, error)         { return m
 func (m *mockStore) GetAllNodes() ([]models.ProbeNode, error)         { return nil, nil }
 func (m *mockStore) UpdateNodeLastSeen(string) error                  { return nil }
 func (m *mockStore) DeleteNode(string) error                          { return nil }
+func (m *mockStore) LoadAlertHealth() (map[int]models.AlertHealthRecord, error) {
+	return nil, nil
+}
+func (m *mockStore) SaveAlertHealth(models.AlertHealthRecord) error { return nil }
 func (m *mockStore) GetActiveMaintenanceWindows() ([]models.MaintenanceWindow, error) {
 	return nil, nil
 }