feat(auth): add Pydantic auth models and unit tests; update docs

src/server/models/auth.py

@@ -0,0 +1,57 @@
+"""Authentication Pydantic models for the Aniworld web application.
+
+This module defines simple request/response shapes used by the auth API and
+by the authentication service. Keep models small and focused so they are
+easy to validate and test.
+"""
+from __future__ import annotations
+
+from datetime import datetime
+from typing import Optional
+
+from pydantic import BaseModel, Field, constr
+
+
+class LoginRequest(BaseModel):
+    """Request body for a login attempt.
+
+    Fields:
+    - password: master password string (minimum 8 chars recommended)
+    - remember: optional flag to request a long-lived session
+    """
+
+    password: constr(min_length=1) = Field(..., description="Master password")
+    remember: Optional[bool] = Field(False, description="Keep session alive")
+
+
+class LoginResponse(BaseModel):
+    """Response returned after a successful login."""
+
+    access_token: str = Field(..., description="JWT access token")
+    token_type: str = Field("bearer", description="Token type")
+    expires_at: Optional[datetime] = Field(None, description="Optional expiry timestamp")
+
+
+class SetupRequest(BaseModel):
+    """Request to initialize the master password during first-time setup."""
+
+    master_password: constr(min_length=8) = Field(..., description="New master password")
+
+
+class AuthStatus(BaseModel):
+    """Public status about whether auth is configured and the current user state."""
+
+    configured: bool = Field(..., description="Whether a master password is set")
+    authenticated: bool = Field(False, description="Whether the caller is authenticated")
+
+
+class SessionModel(BaseModel):
+    """Lightweight session representation stored/returned by the auth service.
+
+    This model can be persisted if a persistent session store is used.
+    """
+
+    session_id: str = Field(..., description="Unique session identifier")
+    user: Optional[str] = Field(None, description="Username or identifier")
+    created_at: datetime = Field(default_factory=datetime.utcnow)
+    expires_at: Optional[datetime] = Field(None)