Extend endpoint and browser tests for ESPNow and UI

Add coverage for /presets/send and updated tab/preset UI workflows in HTTP and Selenium tests.

tests/test_endpoints.py

@@ -332,7 +332,22 @@ def test_presets(client: TestClient) -> bool:
                 else:
                     print(f"✗ PUT /presets/{preset_id} - Status: {response.status_code}")
                 
-                # Test 5: Delete preset
+                # Test 5: Send preset via /presets/send
+                total += 1
+                try:
+                    send_body = {"preset_ids": [preset_id]}
+                    response = client.post('/presets/send', json_data=send_body)
+                    if response.status_code == 200:
+                        data = response.json()
+                        sent = data.get('presets_sent')
+                        print(f"✓ POST /presets/send - Sent presets (presets_sent={sent})")
+                        passed += 1
+                    else:
+                        print(f"✗ POST /presets/send - Status: {response.status_code}, Response: {response.text}")
+                except Exception as e:
+                    print(f"✗ POST /presets/send - Error: {e}")
+                
+                # Test 6: Delete preset
                 total += 1
                 response = client.delete(f'/presets/{preset_id}')
                 if response.status_code == 200: