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_memory.py

@@ -1,58 +0,0 @@
-import pytest
-
-# Import the classes here, assuming the above definitions are in a module named memory_module
-from letta.schemas.memory import ChatMemory, Memory
-
-
-@pytest.fixture
-def sample_memory():
-    return ChatMemory(persona="Chat Agent", human="User")
-
-
-def test_create_chat_memory():
-    """Test creating an instance of ChatMemory"""
-    chat_memory = ChatMemory(persona="Chat Agent", human="User")
-    assert chat_memory.get_block("persona").value == "Chat Agent"
-    assert chat_memory.get_block("human").value == "User"
-
-
-def test_memory_limit_validation(sample_memory: Memory):
-    """Test exceeding memory limit"""
-    with pytest.raises(ValueError):
-        ChatMemory(persona="x " * 50000, human="y " * 50000)
-
-    with pytest.raises(ValueError):
-        sample_memory.get_block("persona").value = "x " * 50000
-
-
-def test_memory_jinja2_set_template(sample_memory: Memory):
-    """Test setting the template for the memory"""
-
-    example_template = sample_memory.get_prompt_template()
-
-    # Try setting a valid template
-    sample_memory.set_prompt_template(prompt_template=example_template)
-
-    # Try setting an invalid template (bad jinja2)
-    template_bad_jinja = (
-        "{% for section, module in mammoth.items() %}"
-        '<{{ section }} characters="{{ module.value|length }}/{{ module.limit }}">\n'
-        "{{ module.value }}\n"
-        "</{{ section }}>"
-        "{% if not loop.last %}\n{% endif %}"
-        "{% endfor %"  # Missing closing curly brace
-    )
-    with pytest.raises(ValueError):
-        sample_memory.set_prompt_template(prompt_template=template_bad_jinja)
-
-    # Try setting an invalid template (not compatible with memory structure)
-    template_bad_memory_structure = (
-        "{% for section, module in mammoth.items() %}"
-        '<{{ section }} characters="{{ module.value|length }}/{{ module.limit }}">\n'
-        "{{ module.value }}\n"
-        "</{{ section }}>"
-        "{% if not loop.last %}\n{% endif %}"
-        "{% endfor %}"
-    )
-    with pytest.raises(ValueError):
-        sample_memory.set_prompt_template(prompt_template=template_bad_memory_structure)