fix: Implement /api/anime/add endpoint correctly

- Fixed 501 Not Implemented error by replacing non-existent AddSeries method
- Added Serie import from src.core.entities.series
- Implemented proper series creation using Serie class following CLI pattern
- Added input validation for empty link and name fields
- Series are now correctly added to series_app.List using add() method
- Call refresh_series_list() to update cache after adding

Tests:
- Added test for unauthorized access (401)
- Added test for successful addition with authentication (200)
- Added test for empty name validation (400)
- Added test for empty link validation (400)
- Updated FakeSeriesApp mock to support add() and refresh_series_list()

All tests passing.

src/server/api/anime.py

@@ -3,6 +3,7 @@ from typing import Any, List, Optional
 from fastapi import APIRouter, Depends, HTTPException, status
 from pydantic import BaseModel, Field
 
+from src.core.entities.series import Serie
 from src.server.utils.dependencies import (
     get_optional_series_app,
     get_series_app,
@@ -540,24 +541,50 @@ async def add_series(
         HTTPException: If adding the series fails
     """
     try:
-        if not hasattr(series_app, "AddSeries"):
-            raise HTTPException(
-                status_code=status.HTTP_501_NOT_IMPLEMENTED,
-                detail="Add series functionality not available",
-            )
-        
-        result = series_app.AddSeries(request.link, request.name)
-        
-        if result:
-            return {
-                "status": "success",
-                "message": f"Successfully added series: {request.name}"
-            }
-        else:
+        # Validate inputs
+        if not request.link or not request.link.strip():
             raise HTTPException(
                 status_code=status.HTTP_400_BAD_REQUEST,
-                detail="Failed to add series - series may already exist",
+                detail="Series link cannot be empty",
             )
+        
+        if not request.name or not request.name.strip():
+            raise HTTPException(
+                status_code=status.HTTP_400_BAD_REQUEST,
+                detail="Series name cannot be empty",
+            )
+        
+        # Check if series_app has the List attribute
+        if not hasattr(series_app, "List"):
+            raise HTTPException(
+                status_code=status.HTTP_501_NOT_IMPLEMENTED,
+                detail="Series list functionality not available",
+            )
+        
+        # Create a new Serie object
+        # Following the pattern from CLI:
+        # Serie(key, name, site, folder, episodeDict)
+        # The key and folder are both the link in this case
+        # episodeDict is empty {} for a new series
+        serie = Serie(
+            key=request.link.strip(),
+            name=request.name.strip(),
+            site="aniworld.to",
+            folder=request.name.strip(),
+            episodeDict={}
+        )
+        
+        # Add the series to the list
+        series_app.List.add(serie)
+        
+        # Refresh the series list to update the cache
+        if hasattr(series_app, "refresh_series_list"):
+            series_app.refresh_series_list()
+        
+        return {
+            "status": "success",
+            "message": f"Successfully added series: {request.name}"
+        }
     except HTTPException:
         raise
     except Exception as exc: