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/user.py

@@ -0,0 +1,50 @@
+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 User(SQLModel, table=True):
+    id: Optional[int] = Field(default=None, primary_key=True)
+    username: str = Field(index=True, unique=True)
+    hashed_password: str
+    role: str = Field(default="user")  # "admin" | "user"
+    is_active: bool = Field(default=True)
+    created_at: datetime = Field(default_factory=_now)
+
+
+# --- API schemas ---
+
+
+class UserRead(SQLModel):
+    id: int
+    username: str
+    role: str
+    is_active: bool
+
+
+class UserCreate(SQLModel):
+    username: str
+    password: str
+    role: str = "admin"
+
+
+class LoginRequest(SQLModel):
+    username: str
+    password: str
+
+
+class TokenPair(SQLModel):
+    access_token: str
+    refresh_token: str
+    token_type: str = "bearer"
+
+
+class RefreshRequest(SQLModel):
+    refresh_token: str