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.

src/everos/core/lifespan/base.py

@@ -0,0 +1,30 @@
+"""Lifespan provider abstract base.
+
+A LifespanProvider is one unit of startup / shutdown work invoked by the
+FastAPI lifespan factory. Providers are registered explicitly (no DI
+auto-discovery) and executed in ``order`` ascending on startup, reverse
+on shutdown.
+"""
+
+from __future__ import annotations
+
+from abc import ABC, abstractmethod
+from typing import Any
+
+from fastapi import FastAPI
+
+
+class LifespanProvider(ABC):
+    """One unit of startup / shutdown work."""
+
+    def __init__(self, name: str, order: int = 0) -> None:
+        self.name = name
+        self.order = order
+
+    @abstractmethod
+    async def startup(self, app: FastAPI) -> Any:
+        """Startup hook; return value is stored on ``app.state.lifespan_data[name]``."""
+
+    @abstractmethod
+    async def shutdown(self, app: FastAPI) -> None:
+        """Shutdown hook; called in reverse order during application teardown."""