fix: resolve import migrations and test failures after segment 3 merge

- Migrate core.model_runtime -> dify_graph.model_runtime across 20+ files
- Migrate core.workflow.file -> dify_graph.file across 15+ files
- Migrate core.workflow.enums -> dify_graph.enums in service files
- Fix SandboxContext phantom import in dify_graph/context/__init__.py
- Fix core.app.workflow.node_factory -> core.workflow.node_factory
- Fix toast import paths (useToastContext from toast/context)
- Fix app-info.tsx import paths for relocated app-operations
- Fix 15 frontend test files for API changes, missing QueryClientProvider,
  i18n key renames, and component behavior changes

Made-with: Cursor

api/core/llm_generator/output_models.py

@@ -2,7 +2,7 @@ from __future__ import annotations
 
 from pydantic import BaseModel, ConfigDict, Field
 
-from core.workflow.variables.types import SegmentType
+from dify_graph.variables.types import SegmentType
 
 
 class SuggestedQuestionsOutput(BaseModel):

api/core/llm_generator/output_parser/file_ref.py

@@ -10,8 +10,8 @@ This module provides utilities to:
 from collections.abc import Callable, Mapping, Sequence
 from typing import Any, cast
 
-from core.workflow.file import File
-from core.workflow.variables.segments import ArrayFileSegment, FileSegment
+from dify_graph.file import File
+from dify_graph.variables.segments import ArrayFileSegment, FileSegment
 
 FILE_PATH_FORMAT = "file-path"
 FILE_PATH_DESCRIPTION_SUFFIX = "this field contains a file path from the Dify sandbox"

api/core/llm_generator/utils.py

@@ -1,6 +1,6 @@
 """Utility functions for LLM generator."""
 
-from core.model_runtime.entities.message_entities import (
+from dify_graph.model_runtime.entities.message_entities import (
     AssistantPromptMessage,
     PromptMessage,
     PromptMessageRole,