Initial commit: StackPilot Phase 1 (Core)

Self-hosted Docker Compose manager.
- Backend: FastAPI + docker-py + SQLite (JWT auth, file-first stacks,
  lifecycle, live status, WebSocket logs, docker-run converter, audit log)
- Frontend: React + Vite + Tailwind (login/setup, dashboard, stacks,
  stack detail, Monaco editor, dark/light theme)
- Deployment: docker-compose.yml, Dockerfiles, nginx reverse proxy

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/models/audit.py

@@ -0,0 +1,20 @@
+from __future__ import annotations
+
+from datetime import datetime, timezone
+from typing import Optional
+
+from sqlmodel import Field, SQLModel
+
+
+def _now() -> datetime:
+    return datetime.now(timezone.utc)
+
+
+class AuditLog(SQLModel, table=True):
+    id: Optional[int] = Field(default=None, primary_key=True)
+    user: str
+    action: str  # e.g. "stack.start"
+    target: str  # stack id / resource id
+    detail: Optional[str] = None
+    ip: Optional[str] = None
+    timestamp: datetime = Field(default_factory=_now, index=True)