chore: initialize EverOS 1.0.0

md-first memory extraction framework for AI agents.

Markdown is the single source of truth; SQLite holds state and LanceDB
provides the rebuildable vector + BM25 + scalar index. The codebase follows
a single-direction DDD layering (entrypoints -> service -> memory -> infra,
with component / core / config cross-cutting) enforced by import-linter.

Engineering surface:
- Coding conventions in .claude/rules/ (path-scoped) and workflows in
  .claude/skills/ (/commit, /new-branch, /pr).
- GitHub Actions CI runs make lint + test + integration; pre-commit mirrors
  the gates locally (ruff, hygiene hooks, gitlint commit-msg).
- Commit messages follow Conventional Commits, enforced by gitlint.
- make lint also enforces datetime two-zone discipline and OpenAPI drift.

tests/unit/test_infra/test_sqlite/test_sqlite_manager.py

@@ -0,0 +1,53 @@
+"""SQLite manager singletons.
+
+Verifies ``get_engine`` / ``get_session_factory`` / ``dispose_engine``
+are idempotent and rebuild after dispose.
+"""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+import pytest
+
+from everos.infra.persistence.sqlite import sqlite_manager
+
+
+@pytest.fixture(autouse=True)
+async def _reset(tmp_path: Path, monkeypatch: pytest.MonkeyPatch):
+    """Point the singleton at an isolated memory-root and reset module state."""
+    monkeypatch.setenv("EVEROS_MEMORY__ROOT", str(tmp_path))
+    sqlite_manager._engine = None
+    sqlite_manager._session_factory = None
+    yield
+    await sqlite_manager.dispose_engine()
+
+
+async def test_get_engine_is_singleton(tmp_path: Path) -> None:
+    e1 = sqlite_manager.get_engine()
+    e2 = sqlite_manager.get_engine()
+    assert e1 is e2
+    # Engine points at the redirected memory root.
+    assert str(tmp_path) in str(e1.url)
+
+
+async def test_get_session_factory_is_singleton() -> None:
+    f1 = sqlite_manager.get_session_factory()
+    f2 = sqlite_manager.get_session_factory()
+    assert f1 is f2
+
+
+async def test_dispose_resets_state() -> None:
+    e1 = sqlite_manager.get_engine()
+    await sqlite_manager.dispose_engine()
+    assert sqlite_manager._engine is None
+    assert sqlite_manager._session_factory is None
+    e2 = sqlite_manager.get_engine()
+    assert e2 is not e1
+
+
+async def test_dispose_is_idempotent() -> None:
+    await sqlite_manager.dispose_engine()  # nothing built yet
+    sqlite_manager.get_engine()
+    await sqlite_manager.dispose_engine()
+    await sqlite_manager.dispose_engine()  # second call must not raise