feat: add image_path to recipe/subtask and user password change API

- Recipe model: add image_path field for recipe-level image
- RecipeSubtask model: add image_path for per-subtask detail images
- Schemas: add image_path to create/update/response for recipe and subtask
- Task router: pass image_path when creating tasks and subtasks
- Recipe service: copy image_path in versioning and update-in-place
- Users router: add PUT /{user_id}/password endpoint (admin only)
- User schema: add UserPasswordChange model

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

server/models/task.py

@@ -69,6 +69,7 @@ class RecipeSubtask(Base):
     ltl: Mapped[Optional[float]] = mapped_column(DECIMAL(12, 6), nullable=True)  # Lower Tolerance Limit
 
     unit: Mapped[str] = mapped_column(String(20), nullable=False, default="mm")
+    image_path: Mapped[Optional[str]] = mapped_column(String(500), nullable=True)
 
     # Relationships
     task: Mapped["RecipeTask"] = relationship(back_populates="subtasks")