Add AI-powered nutrition and plan modules

Introduces DSPy-based nutrition and plan generation modules, including image analysis for nutritional info and personalized diet/exercise plans. Adds new API endpoints for health metrics/goals, nutrition image analysis, and plan management. Updates models, schemas, and backend structure to support these features, and includes initial training data and configuration for prompt optimization.

backend/app/main.py

@@ -1,12 +1,12 @@
 from contextlib import asynccontextmanager
-from dotenv import load_dotenv
-
-load_dotenv()
 
 from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+
 from app.api.v1.api import api_router
-from app.db import init_db
 from app.core.ai_config import configure_dspy
+from app.db import init_db
+
 
 @asynccontextmanager
 async def lifespan(app: FastAPI):
@@ -14,7 +14,6 @@ async def lifespan(app: FastAPI):
     configure_dspy()
     yield
 
-from fastapi.middleware.cors import CORSMiddleware
 
 app = FastAPI(title="Healthy Fit API", lifespan=lifespan)
 
@@ -28,6 +27,7 @@ app.add_middleware(
 
 app.include_router(api_router, prefix="/api/v1")
 
+
 @app.get("/")
 def read_root():
     return {"message": "Welcome to Healthy Fit API"}