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>

tests/test_cli.py

@@ -1,90 +0,0 @@
-import os
-import re
-import shutil
-import sys
-
-import pexpect
-import pytest
-
-from letta.local_llm.constants import ASSISTANT_MESSAGE_CLI_SYMBOL, INNER_THOUGHTS_CLI_SYMBOL
-
-original_letta_path = os.path.expanduser("~/.letta")
-backup_letta_path = os.path.expanduser("~/.letta_backup")
-
-
-@pytest.fixture
-def swap_letta_config():
-    if os.path.exists(backup_letta_path):
-        print("\nDelete the backup ~/.letta directory\n")
-        shutil.rmtree(backup_letta_path)
-
-    if os.path.exists(original_letta_path):
-        print("\nBackup the original ~/.letta directory\n")
-        shutil.move(original_letta_path, backup_letta_path)
-
-    try:
-        # Run the test
-        yield
-    finally:
-        # Ensure this runs no matter what
-        print("\nClean up ~/.letta and restore the original directory\n")
-        if os.path.exists(original_letta_path):
-            shutil.rmtree(original_letta_path)
-
-        if os.path.exists(backup_letta_path):
-            shutil.move(backup_letta_path, original_letta_path)
-
-
-def test_letta_run_create_new_agent(swap_letta_config):
-    child = pexpect.spawn("uv run letta run", encoding="utf-8")
-    # Start the letta run command
-    child.logfile = sys.stdout
-    child.expect("Creating new agent", timeout=20)
-    # Optional: LLM model selection
-    try:
-        child.expect("Select LLM model:", timeout=20)
-        child.sendline("")
-    except (pexpect.TIMEOUT, pexpect.EOF):
-        print("[WARNING] LLM model selection step was skipped.")
-
-    # Optional: Context window selection
-    try:
-        child.expect("Select LLM context window limit", timeout=20)
-        child.sendline("")
-    except (pexpect.TIMEOUT, pexpect.EOF):
-        print("[WARNING] Context window selection step was skipped.")
-
-    # Optional: Embedding model selection
-    try:
-        child.expect("Select embedding model:", timeout=20)
-        child.sendline("text-embedding-3-small")
-    except (pexpect.TIMEOUT, pexpect.EOF):
-        print("[WARNING] Embedding model selection step was skipped.")
-
-    child.expect("Created new agent", timeout=20)
-    child.sendline("")
-
-    # Get initial response
-    child.expect("Enter your message:", timeout=60)
-    # Capture the output up to this point
-    full_output = child.before
-    assert full_output is not None, "No output was captured."
-    # Count occurrences of inner thoughts
-    cloud_emoji_count = full_output.count(INNER_THOUGHTS_CLI_SYMBOL)
-    assert cloud_emoji_count == 1, "It appears that there are multiple instances of inner thought outputted."
-    # Count occurrences of assistant messages
-    robot = full_output.count(ASSISTANT_MESSAGE_CLI_SYMBOL)
-    assert robot == 1, "It appears that there are multiple instances of assistant messages outputted."
-
-
-def test_letta_version_prints_only_version(swap_letta_config):
-    # Start the letta version command
-    output = pexpect.run("uv run letta version", encoding="utf-8")
-
-    # Remove ANSI escape sequences and whitespace
-    output = re.sub(r"\x1b\[[0-9;]*[mK]", "", output).strip()
-
-    from letta import __version__
-
-    # Get the full output and verify it contains only the version
-    assert output == __version__, f"Expected only '{__version__}', but got '{repr(output)}'"