feat(trackers): user filters for Gitea, webhook polling cleanup, dashboard navigability

- Gitea: NotificationTracker now exposes sender allowlist / blocklist filters
  via MultiEntitySelect, populated from Gitea /users/search merged with past
  EventLog senders so the picker is useful before the first webhook arrives.
- Webhook providers (gitea, planka, webhook): stop scheduling interval polling
  jobs on tracker create/update/startup; hide the "every Xs" indicator in the
  tracker list since there is no polling.
- Dashboard: stat cards are now <a> links that route to providers, trackers,
  targets, command-trackers, or scroll to the events panel. Provider deck
  rows highlight the target provider on click.
- Command trackers / command configs: auto-reselect the right config when the
  provider type changes (matches notification-tracker behavior).
- Migration: drop legacy batch_duration column from notification_tracker —
  the field is gone from the model but its NOT NULL constraint blocked
  inserts on older DBs.
- Docs: refresh entity-relationships.md with current NotificationTracker
  fields (filters, adaptive_max_skip, default_*_config_id).

frontend/src/routes/command-configs/+page.svelte

@@ -110,6 +110,27 @@
 		editing = null;
 		showForm = true;
 	}
+
+	// Re-pick the command-template config when the provider type changes.
+	// The previously-selected id may belong to a different provider type and
+	// would no longer appear in the filtered EntitySelect, leaving it empty.
+	let _prevProviderType = $state('');
+	$effect(() => {
+		if (showForm && form.provider_type && form.provider_type !== _prevProviderType) {
+			_prevProviderType = form.provider_type;
+			if (editing === null) {
+				const currentTpl = cmdTemplateConfigs.find(
+					(c) => c.id === form.command_template_config_id,
+				);
+				if (!currentTpl || currentTpl.provider_type !== form.provider_type) {
+					const first = cmdTemplateConfigs.find(
+						(c) => c.provider_type === form.provider_type,
+					);
+					form.command_template_config_id = first?.id ?? null;
+				}
+			}
+		}
+	});
 	function editConfig(cfg: CommandConfig) {
 		form = {
 			name: cfg.name,