fix: resolve frontend/backend integration bugs

- Rename skincare route prefix /skin-snapshots → /skincare to match API client
- Add redirect_slashes=False to FastAPI app; change collection routes from "/" to ""
  to eliminate 307 redirects on POST/GET without trailing slash
- Fix redirect() inside try/catch in products/new and routines/new server actions
  (SvelteKit redirect() throws and was being caught as a 500 error)
- Eagerly load inventory and steps relationships via explicit SELECT + model_dump(mode="json"),
  working around SQLModel 0.0.37 not serializing Relationship fields in response_model
- Add field_validator for product_effect_profile to coerce DB-returned dict → ProductEffectProfile,
  eliminating Pydantic serializer warning
- Update all tests to use routes without trailing slash

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

backend/innercontext/api/products.py

@@ -188,7 +188,7 @@ def get_or_404(session: Session, model, record_id) -> object:
 # ---------------------------------------------------------------------------
 
 
-@router.get("/", response_model=list[Product])
+@router.get("", response_model=list[Product])
 def list_products(
     category: Optional[ProductCategory] = None,
     brand: Optional[str] = None,
@@ -224,7 +224,7 @@ def list_products(
     return products
 
 
-@router.post("/", response_model=Product, status_code=201)
+@router.post("", response_model=Product, status_code=201)
 def create_product(data: ProductCreate, session: Session = Depends(get_session)):
     product = Product(
         id=uuid4(),
@@ -236,9 +236,13 @@ def create_product(data: ProductCreate, session: Session = Depends(get_session))
     return product
 
 
-@router.get("/{product_id}", response_model=Product)
+@router.get("/{product_id}")
 def get_product(product_id: UUID, session: Session = Depends(get_session)):
-    return get_or_404(session, Product, product_id)
+    product = get_or_404(session, Product, product_id)
+    inventory = session.exec(select(ProductInventory).where(ProductInventory.product_id == product_id)).all()
+    data = product.model_dump(mode="json")
+    data["inventory"] = [item.model_dump(mode="json") for item in inventory]
+    return data
 
 
 @router.patch("/{product_id}", response_model=Product)

backend/innercontext/api/routines.py

@@ -76,7 +76,7 @@ def get_or_404(session: Session, model, record_id) -> object:
 # ---------------------------------------------------------------------------
 
 
-@router.get("/", response_model=list[Routine])
+@router.get("", response_model=list[Routine])
 def list_routines(
     from_date: Optional[date] = None,
     to_date: Optional[date] = None,
@@ -93,7 +93,7 @@ def list_routines(
     return session.exec(stmt).all()
 
 
-@router.post("/", response_model=Routine, status_code=201)
+@router.post("", response_model=Routine, status_code=201)
 def create_routine(data: RoutineCreate, session: Session = Depends(get_session)):
     routine = Routine(id=uuid4(), **data.model_dump())
     session.add(routine)
@@ -108,9 +108,13 @@ def list_grooming_schedule(session: Session = Depends(get_session)):
     return session.exec(select(GroomingSchedule)).all()
 
 
-@router.get("/{routine_id}", response_model=Routine)
+@router.get("/{routine_id}")
 def get_routine(routine_id: UUID, session: Session = Depends(get_session)):
-    return get_or_404(session, Routine, routine_id)
+    routine = get_or_404(session, Routine, routine_id)
+    steps = session.exec(select(RoutineStep).where(RoutineStep.routine_id == routine_id)).all()
+    data = routine.model_dump(mode="json")
+    data["steps"] = [step.model_dump(mode="json") for step in steps]
+    return data
 
 
 @router.patch("/{routine_id}", response_model=Routine)

backend/innercontext/api/skincare.py

@@ -78,7 +78,7 @@ def get_or_404(session: Session, model, record_id) -> object:
 # ---------------------------------------------------------------------------
 
 
-@router.get("/", response_model=list[SkinConditionSnapshot])
+@router.get("", response_model=list[SkinConditionSnapshot])
 def list_snapshots(
     from_date: Optional[date] = None,
     to_date: Optional[date] = None,
@@ -95,7 +95,7 @@ def list_snapshots(
     return session.exec(stmt).all()
 
 
-@router.post("/", response_model=SkinConditionSnapshot, status_code=201)
+@router.post("", response_model=SkinConditionSnapshot, status_code=201)
 def create_snapshot(
     data: SnapshotCreate, session: Session = Depends(get_session)
 ):

backend/innercontext/models/product.py

@@ -2,7 +2,7 @@ from datetime import date, datetime
 from typing import ClassVar, Optional
 from uuid import UUID, uuid4
 
-from pydantic import model_validator
+from pydantic import field_validator, model_validator
 from sqlalchemy import JSON, Column, DateTime
 from sqlmodel import Field, Relationship, SQLModel
 
@@ -188,6 +188,13 @@ class Product(SQLModel, table=True):
 
     inventory: list["ProductInventory"] = Relationship(back_populates="product")
 
+    @field_validator("product_effect_profile", mode="before")
+    @classmethod
+    def coerce_effect_profile(cls, v: object) -> object:
+        if isinstance(v, dict):
+            return ProductEffectProfile(**v)
+        return v
+
     @model_validator(mode="after")
     def validate_business_rules(self) -> "Product":
         if (