Backend: product sub-choices, sort_order, preference shared_subset, hard-delete

- ProductOption and ProductPreferenceChoice gain sub_choices (JSON Text column)
  for nested inline choices shown when the parent is selected
- ProductPreferenceSet gains default_choice_id and shared_subset (set-level
  sub-choice group shown for all choices that don't disable it)
- Product gains sort_order column; list endpoint orders by sort_order
- New PUT /products/reorder endpoint for drag-and-drop ordering
- DELETE /products/{id} now accepts ?hard=true for permanent deletion (blocked
  if product appears in any past order)
- Schemas updated with model_validators to parse stored JSON back to typed objects
- Add python-multipart to requirements (needed for file upload form parsing)

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

local_backend/models/product.py

@@ -1,4 +1,4 @@
-from sqlalchemy import Column, Integer, String, Boolean, Float, ForeignKey
+from sqlalchemy import Column, Integer, String, Boolean, Float, ForeignKey, Text
 from sqlalchemy.orm import relationship
 from database import Base
 
@@ -24,6 +24,7 @@ class Product(Base):
     is_available = Column(Boolean, default=True, nullable=False)
     printer_zone_id = Column(Integer, ForeignKey("printers.id"), nullable=True)
     image_url = Column(String, nullable=True)
+    sort_order = Column(Integer, default=0, nullable=False)
 
     category = relationship("Category", back_populates="products")
     printer_zone = relationship("Printer", back_populates="products")
@@ -40,6 +41,8 @@ class ProductOption(Base):
     product_id = Column(Integer, ForeignKey("products.id"), nullable=False)
     name = Column(String, nullable=False)
     extra_cost = Column(Float, default=0.0)
+    # JSON array [{name, extra_cost, is_default}] — sub-options shown when this option is checked
+    sub_choices = Column(Text, nullable=True)
 
     product = relationship("Product", back_populates="options")
 
@@ -61,6 +64,10 @@ class ProductPreferenceSet(Base):
     id = Column(Integer, primary_key=True, index=True)
     product_id = Column(Integer, ForeignKey("products.id"), nullable=False)
     name = Column(String, nullable=False)
+    default_choice_id = Column(Integer, nullable=True)
+    # JSON: {name, default_choice_index, choices:[{name,extra_cost,is_default}]}
+    # Shared sub-set shown for all choices that don't have disables_subset=True
+    shared_subset = Column(Text, nullable=True)
 
     product = relationship("Product", back_populates="preference_sets")
     choices = relationship("ProductPreferenceChoice", back_populates="set", cascade="all, delete-orphan")
@@ -73,5 +80,10 @@ class ProductPreferenceChoice(Base):
     set_id = Column(Integer, ForeignKey("product_preference_sets.id"), nullable=False)
     name = Column(String, nullable=False)
     extra_cost = Column(Float, default=0.0)
+    # JSON array of sub-choice objects: [{name, extra_cost, is_default}]
+    # Per-choice inline sub-preference shown only when this choice is selected.
+    sub_choices = Column(Text, nullable=True)
+    # When True this choice hides the set-level shared_subset on the PWA.
+    disables_subset = Column(Boolean, default=False, nullable=False)
 
     set = relationship("ProductPreferenceSet", back_populates="choices")