Add major caching to sampler manager

Signed-off-by: Felipe Cardoso <felipe.cardoso@hotmail.it>

backend/app/api/routes/samples.py

@@ -1,16 +1,15 @@
 from typing import List
 
-from fastapi import APIRouter, HTTPException, Query
+from fastapi import APIRouter, HTTPException, Query, Request
 from fastapi.responses import Response
 
 from app.models.sample import Sample
-from app.services.sample_manager import SampleManager
 
 router = APIRouter()
-sample_manager = SampleManager()
 
 @router.get("/list", response_model=List[Sample])
 async def list_samples(
+        request: Request,
         limit: int = Query(20, ge=1, le=100),
         offset: int = Query(0, ge=0)
 ):
@@ -18,31 +17,36 @@ async def list_samples(
     List sample images with pagination
     """
     try:
+        sample_manager = request.app.state.sample_manager
         return await sample_manager.list_samples(limit, offset)
     except Exception as e:
         raise HTTPException(status_code=500, detail=str(e))
 
 @router.get("/latest", response_model=List[Sample])
 async def get_latest_samples(
+        request: Request,
         count: int = Query(5, ge=1, le=20)
 ):
     """
     Get the most recent sample images
     """
     try:
+        sample_manager = request.app.state.sample_manager
         return await sample_manager.get_latest_samples(count)
     except Exception as e:
         raise HTTPException(status_code=500, detail=str(e))
 
 
 @router.get("/image/{filename}")
-async def get_sample_image(filename: str):
+async def get_sample_image(
+        request: Request,
+        filename: str):
     """
     Get a specific sample image
     """
     try:
+        sample_manager = request.app.state.sample_manager
         image_data = await sample_manager.get_sample_data(filename)
-
         # Try to determine content type from filename
         content_type = "image/jpeg"  # default
         if filename.lower().endswith('.png'):