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/cli/cli.py

@@ -1,49 +0,0 @@
-import sys
-from enum import Enum
-from typing import Annotated, Optional
-
-import typer
-
-from letta.log import get_logger
-from letta.streaming_interface import StreamingRefreshCLIInterface as interface  # for printing to terminal
-
-logger = get_logger(__name__)
-
-
-class ServerChoice(Enum):
-    rest_api = "rest"
-    ws_api = "websocket"
-
-
-def server(
-    type: Annotated[ServerChoice, typer.Option(help="Server to run")] = "rest",
-    port: Annotated[Optional[int], typer.Option(help="Port to run the server on")] = None,
-    host: Annotated[Optional[str], typer.Option(help="Host to run the server on (default to localhost)")] = None,
-    debug: Annotated[bool, typer.Option(help="Turn debugging output on")] = False,
-    reload: Annotated[bool, typer.Option(help="Enable hot-reload")] = False,
-    ade: Annotated[bool, typer.Option(help="Allows remote access")] = False,  # NOTE: deprecated
-    secure: Annotated[bool, typer.Option(help="Adds simple security access")] = False,
-    localhttps: Annotated[bool, typer.Option(help="Setup local https")] = False,
-):
-    """Launch a Letta server process"""
-    if type == ServerChoice.rest_api:
-        pass
-
-        try:
-            from letta.server.rest_api.app import start_server
-
-            start_server(port=port, host=host, debug=debug, reload=reload)
-
-        except KeyboardInterrupt:
-            # Handle CTRL-C
-            typer.secho("Terminating the server...")
-            sys.exit(0)
-
-    elif type == ServerChoice.ws_api:
-        raise NotImplementedError("WS suppport deprecated")
-
-
-def version() -> str:
-    import letta
-
-    print(letta.__version__)