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/routers/tasks.py

@@ -175,6 +175,7 @@ async def create_task(
         title=data.title,
         directive=data.directive,
         description=data.description,
+        file_path=data.file_path,
         file_type=data.file_type,
         annotations_json=data.annotations_json,
     )
@@ -194,6 +195,7 @@ async def create_task(
             lwl=sub_data.lwl,
             ltl=sub_data.ltl,
             unit=sub_data.unit,
+            image_path=sub_data.image_path,
         )
         db.add(sub)
 
@@ -333,6 +335,7 @@ async def create_subtask(
         lwl=data.lwl,
         ltl=data.ltl,
         unit=data.unit,
+        image_path=data.image_path,
     )
     db.add(subtask)
     await db.flush()