webui: add "delete all conversations" button to import/export tab (#17444)

* webui: add "delete all conversations" button to import/export tab

- Add 'Delete all conversations' functionality with confirmation dialog
- Add Trash icon and destructive styling for clear visual indication
- Redirects to "?new_chat=true#/" by using conversationsStore.deleteAll()

* chore: update webui build output

tools/server/webui/src/lib/stores/conversations.svelte.ts

@@ -385,8 +385,7 @@ class ConversationsStore {
 			this.conversations = this.conversations.filter((c) => c.id !== convId);
 
 			if (this.activeConversation?.id === convId) {
-				this.activeConversation = null;
-				this.activeMessages = [];
+				this.clearActiveConversation();
 				await goto(`?new_chat=true#/`);
 			}
 		} catch (error) {
@@ -394,6 +393,29 @@ class ConversationsStore {
 		}
 	}
 
+	/**
+	 * Deletes all conversations and their messages
+	 */
+	async deleteAll(): Promise<void> {
+		try {
+			const allConversations = await DatabaseService.getAllConversations();
+
+			for (const conv of allConversations) {
+				await DatabaseService.deleteConversation(conv.id);
+			}
+
+			this.clearActiveConversation();
+			this.conversations = [];
+
+			toast.success('All conversations deleted');
+
+			await goto(`?new_chat=true#/`);
+		} catch (error) {
+			console.error('Failed to delete all conversations:', error);
+			toast.error('Failed to delete conversations');
+		}
+	}
+
 	// ─────────────────────────────────────────────────────────────────────────────
 	// Import/Export
 	// ─────────────────────────────────────────────────────────────────────────────