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/api/v1/endpoints/plans.py

@@ -0,0 +1,67 @@
+from typing import Any, List
+
+from fastapi import APIRouter, Depends, HTTPException
+from pydantic import BaseModel
+from sqlmodel import Session, select
+
+from app.ai.plans import plan_module
+from app.api import deps
+from app.models.plan import Plan
+
+router = APIRouter()
+
+
+class PlanRequest(BaseModel):
+    goal: str
+    user_details: str  # e.g., "Male, 30, 80kg"
+
+
+@router.post("/generate", response_model=Plan)
+def generate_plan(
+    *,
+    current_user: deps.CurrentUser,
+    request: PlanRequest,
+    session: Session = Depends(deps.get_session),
+) -> Any:
+    """
+    Generate a new diet/exercise plan using AI.
+    """
+    try:
+        # Generate plan using DSPy
+        generated = plan_module(user_profile=request.user_details, goal=request.goal)
+
+        # Determine content string (markdown representation)
+        content_md = (
+            f"# {generated.plan.title}\n\n{generated.plan.summary}\n\n## Diet\n"
+            + "\n".join([f"- {item}" for item in generated.plan.diet_plan])
+            + "\n\n## Exercise\n"
+            + "\n".join([f"- {item}" for item in generated.plan.exercise_plan])
+            + "\n\n## Tips\n"
+            + "\n".join([f"- {item}" for item in generated.plan.tips])
+        )
+
+        plan = Plan(
+            user_id=current_user.id,
+            goal=request.goal,
+            content=content_md,
+            structured_content=generated.plan.model_dump(),
+        )
+        session.add(plan)
+        session.commit()
+        session.refresh(plan)
+        return plan
+    except Exception as e:
+        raise HTTPException(status_code=500, detail=str(e))
+
+
+@router.get("/", response_model=List[Plan])
+def read_plans(
+    current_user: deps.CurrentUser,
+    session: Session = Depends(deps.get_session),
+) -> Any:
+    """
+    Get all plans for the current user.
+    """
+    statement = select(Plan).where(Plan.user_id == current_user.id).order_by(Plan.created_at.desc())
+    plans = session.exec(statement).all()
+    return plans