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/schemas/task.py

@@ -15,6 +15,7 @@ class SubtaskCreate(BaseModel):
     lwl: Optional[float] = None
     ltl: Optional[float] = None
     unit: str = Field("mm", max_length=20)
+    image_path: Optional[str] = Field(None, max_length=500)
 
 
 class SubtaskUpdate(BaseModel):
@@ -27,6 +28,7 @@ class SubtaskUpdate(BaseModel):
     lwl: Optional[float] = None
     ltl: Optional[float] = None
     unit: Optional[str] = Field(None, max_length=20)
+    image_path: Optional[str] = Field(None, max_length=500)
 
 
 class SubtaskResponse(BaseModel):
@@ -44,6 +46,7 @@ class SubtaskResponse(BaseModel):
     lwl: Optional[float] = None
     ltl: Optional[float] = None
     unit: str
+    image_path: Optional[str] = None
 
 
 class TaskCreate(BaseModel):