chore: officially migrate to submodule (#4502)

* remove apps/core and apps/fern

* fix precommit

* add submodule updates in workflows

* submodule

* remove core tests

* update core revision

* Add submodules: true to all GitHub workflows

- Ensure all workflows can access git submodules
- Add submodules support to deployment, test, and CI workflows
- Fix YAML syntax issues in workflow files

🤖 Generated with [Claude Code](https://claude.ai/code)

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

* remove core-lint

* upgrade core with latest main of oss

---------

Co-authored-by: Claude <noreply@anthropic.com>

letta/services/tool_executor/tool_executor_base.py

@@ -1,46 +0,0 @@
-from abc import ABC, abstractmethod
-from typing import Any, Dict, Optional
-
-from letta.schemas.agent import AgentState
-from letta.schemas.sandbox_config import SandboxConfig
-from letta.schemas.tool import Tool
-from letta.schemas.tool_execution_result import ToolExecutionResult
-from letta.schemas.user import User
-from letta.services.agent_manager import AgentManager
-from letta.services.block_manager import BlockManager
-from letta.services.job_manager import JobManager
-from letta.services.message_manager import MessageManager
-from letta.services.passage_manager import PassageManager
-
-
-class ToolExecutor(ABC):
-    """Abstract base class for tool executors."""
-
-    def __init__(
-        self,
-        message_manager: MessageManager,
-        agent_manager: AgentManager,
-        block_manager: BlockManager,
-        job_manager: JobManager,
-        passage_manager: PassageManager,
-        actor: User,
-    ):
-        self.message_manager = message_manager
-        self.agent_manager = agent_manager
-        self.block_manager = block_manager
-        self.job_manager = job_manager
-        self.passage_manager = passage_manager
-        self.actor = actor
-
-    @abstractmethod
-    async def execute(
-        self,
-        function_name: str,
-        function_args: dict,
-        tool: Tool,
-        actor: User,
-        agent_state: Optional[AgentState] = None,
-        sandbox_config: Optional[SandboxConfig] = None,
-        sandbox_env_vars: Optional[Dict[str, Any]] = None,
-    ) -> ToolExecutionResult:
-        """Execute the tool and return the result."""