Add feed deletion and single video addition features

- Implemented DELETE /api/channels/<id> to remove channels and cleanup downloaded files
- Added delete button to channels page with confirmation dialog
- Added functionality to add single videos via URL
- Updated navigation menu

templates/channels.html

@@ -29,6 +29,9 @@
                         <button class="btn btn-secondary" onclick="refreshChannel({{ channel.id }})">
                             Refresh Videos
                         </button>
+                        <button class="btn btn-danger" onclick="deleteChannel({{ channel.id }}, '{{ channel.title|replace("'", "\\'") }}')">
+                            Delete
+                        </button>
                         <a href="/?channel={{ channel.id }}" class="btn btn-link">View Videos</a>
                     </div>
                 </div>
@@ -71,5 +74,36 @@
             button.textContent = 'Refresh Videos';
         });
     }
+
+    function deleteChannel(channelId, channelTitle) {
+        if (!confirm(`Are you sure you want to delete "${channelTitle}"?\n\nThis will permanently remove:\n- The channel subscription\n- All video history\n- ALL downloaded video files for this channel\n\nThis action cannot be undone.`)) {
+            return;
+        }
+
+        const button = event.target;
+        const originalText = button.textContent;
+        button.disabled = true;
+        button.textContent = 'Deleting...';
+
+        fetch(`/api/channels/${channelId}`, {
+            method: 'DELETE'
+        })
+        .then(response => response.json())
+        .then(data => {
+            if (data.status === 'success') {
+                alert(data.message);
+                location.reload();
+            } else {
+                alert('Failed to delete: ' + data.message);
+                button.disabled = false;
+                button.textContent = originalText;
+            }
+        })
+        .catch(error => {
+            alert('Error: ' + error);
+            button.disabled = false;
+            button.textContent = originalText;
+        });
+    }
 </script>
 {% endblock %}