feat: UX improvements — secure webhooks, locale fixes, dynamic languages, UI polish

- Remove top paginator from dashboard events, keep only bottom
- Fix test message locale: pass UI locale to email/matrix bot tests
- Convert webhook auth mode from text input to icon grid selector
- Generate secure UUID tokens for webhook URLs instead of sequential IDs
- Move Recent Payloads into per-provider expandable container (lazy-loaded)
- Make template config languages dynamic via app settings instead of hardcoded
- Change default dev port to 5175

frontend/src/lib/providers/gitea.ts

@@ -56,5 +56,5 @@ export const giteaDescriptor: ProviderDescriptor = {
 		desc: () => '',
 	},
 
-	webhookUrlPattern: '/api/webhooks/gitea/{id}',
+	webhookUrlPattern: '/api/webhooks/gitea/{token}',
 };

frontend/src/lib/providers/planka.ts

@@ -62,5 +62,5 @@ export const plankaDescriptor: ProviderDescriptor = {
 		desc: () => '',
 	},
 
-	webhookUrlPattern: '/api/webhooks/planka/{id}',
+	webhookUrlPattern: '/api/webhooks/planka/{token}',
 };

frontend/src/lib/providers/types.ts

@@ -20,7 +20,10 @@ export interface ConfigField {
 	configKey?: string;
 	/** i18n key for the field label. */
 	label: string;
-	type: 'text' | 'password' | 'number';
+	type: 'text' | 'password' | 'number' | 'grid-select';
+	/** Grid-select item source function name from grid-items.ts. */
+	gridItems?: string;
+	gridColumns?: number;
 	placeholder?: string;
 	/**
 	 * - `true`  → always required

frontend/src/lib/providers/webhook.ts

@@ -10,10 +10,10 @@ export const webhookDescriptor: ProviderDescriptor = {
 		{
 			key: 'auth_mode', configKey: 'auth_mode',
 			label: 'providers.authMode',
-			type: 'text',
-			placeholder: 'hmac_sha256 | bearer_token | none',
+			type: 'grid-select',
+			gridItems: 'webhookAuthModeItems',
+			gridColumns: 3,
 			defaultValue: 'none',
-			hint: 'providers.authModeHint',
 		},
 		{
 			key: 'webhook_secret', configKey: 'webhook_secret',
@@ -57,6 +57,6 @@ export const webhookDescriptor: ProviderDescriptor = {
 
 	collectionMeta: null,
 	webhookBased: true,
-	webhookUrlPattern: '/api/webhooks/webhook/{id}',
+	webhookUrlPattern: '/api/webhooks/webhook/{token}',
 	payloadHistory: true,
 };