fix: align Freepik API paths with OpenAPI spec

The original implementation used guessed endpoint paths that don't match
the actual Freepik API. Key fixes based on their OpenAPI spec:

- Task polling is per-endpoint (e.g. GET /v1/ai/text-to-image/flux-dev/{task-id})
  not a generic /v1/ai/tasks/{id}. freepik_client now returns TaskResult
  with status_path, and task_tracker polls using that path.
- Fixed endpoint paths: flux-pro -> flux-pro-v1-1, upscale -> image-upscaler,
  relight -> image-relight, style-transfer -> image-style-transfer,
  expand -> image-expand/flux-pro, inpaint -> ideogram-image-edit,
  remove-background -> beta/remove-background, classifier -> classifier/image,
  audio-isolate -> audio-isolation, icon -> text-to-icon
- Fixed video paths: kling -> kling-o1-pro with kling-o1 status path,
  minimax -> minimax-hailuo-02-1080p, seedance -> seedance-pro-1080p
- Fixed request schemas to match actual API params (e.g. scale_factor
  not scale, reference_image not style_reference, image_url for bg removal)
- Fixed response parsing: status is uppercase (COMPLETED not completed),
  results in data.generated[] array, classifier returns [{class_name, probability}]

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/routers/utilities.py

@@ -1,30 +1,28 @@
-import base64
 import logging
 from datetime import datetime, timezone
 
 from fastapi import APIRouter, HTTPException
 
 from app.schemas.common import TaskResponse, TaskStatus
-from app.schemas.utilities import ClassificationResponse, IconRequest
+from app.schemas.utilities import (
+    ClassificationResponse,
+    IconRequest,
+    RemoveBackgroundRequest,
+    RemoveBackgroundResponse,
+)
 from app.services import freepik_client, task_tracker
+from app.services.freepik_client import _extract_task_id
 
 logger = logging.getLogger(__name__)
 
 router = APIRouter(prefix='/api/v1/util', tags=['utilities'])
 
 
-@router.post('/remove-background')
-async def remove_background(request: dict):
-    """Remove background from an image. Returns processed image as base64."""
-    image = request.get('image')
-    if not image:
-        raise HTTPException(status_code=400, detail='image field is required')
-
-    result_bytes = await freepik_client.remove_background(image)
-    return {
-        'image': base64.b64encode(result_bytes).decode(),
-        'content_type': 'image/png',
-    }
+@router.post('/remove-background', response_model=RemoveBackgroundResponse)
+async def remove_background(request: RemoveBackgroundRequest):
+    """Remove background from an image. Takes a URL, returns result URLs."""
+    result = await freepik_client.remove_background(request.image_url)
+    return RemoveBackgroundResponse(**result)
 
 
 @router.post('/classify', response_model=ClassificationResponse)
@@ -35,12 +33,7 @@ async def classify_image(request: dict):
         raise HTTPException(status_code=400, detail='image field is required')
 
     result = await freepik_client.classify_image(image)
-    data = result.get('data', result)
-    return ClassificationResponse(
-        is_ai_generated=data.get('is_ai_generated', False),
-        ai_probability=data.get('ai_probability', 0.0),
-        human_probability=data.get('human_probability', 0.0),
-    )
+    return result
 
 
 @router.post('/audio-isolate', response_model=TaskResponse)
@@ -51,12 +44,11 @@ async def audio_isolate(request: dict):
         raise HTTPException(status_code=400, detail='audio field is required')
 
     result = await freepik_client.isolate_audio(audio)
-    data = result.get('data', result)
-    freepik_task_id = str(data.get('task_id') or data.get('id', ''))
+    freepik_task_id = _extract_task_id(result.data)
     if not freepik_task_id:
         raise HTTPException(status_code=502, detail='No task_id in Freepik response')
 
-    internal_id = task_tracker.submit(freepik_task_id, {'operation': 'audio-isolate'})
+    internal_id = task_tracker.submit(freepik_task_id, result.status_path, {'operation': 'audio-isolate'})
     return TaskResponse(
         task_id=internal_id,
         status=TaskStatus.pending,
@@ -76,12 +68,11 @@ async def generate_icon(request: IconRequest):
         shape=request.shape,
         style=request.style,
     )
-    data = result.get('data', result)
-    freepik_task_id = str(data.get('task_id') or data.get('id', ''))
+    freepik_task_id = _extract_task_id(result.data)
     if not freepik_task_id:
         raise HTTPException(status_code=502, detail='No task_id in Freepik response')
 
-    internal_id = task_tracker.submit(freepik_task_id, {'operation': 'icon'})
+    internal_id = task_tracker.submit(freepik_task_id, result.status_path, {'operation': 'icon'})
     return TaskResponse(
         task_id=internal_id,
         status=TaskStatus.pending,