feat: Stage 2 — authentication and setup flow

Backend (tasks 2.1–2.6, 2.10):
- settings_repo: get/set/delete/get_all CRUD for the key-value settings table
- session_repo: create/get/delete/delete_expired for session rows
- setup_service: bcrypt password hashing, one-time-only enforcement,
  run_setup() / is_setup_complete() / get_password_hash()
- auth_service: login() with bcrypt verify + token creation,
  validate_session() with expiry check, logout()
- setup router: GET /api/setup (status), POST /api/setup (201 / 409)
- auth router: POST /api/auth/login (token + HttpOnly cookie),
               POST /api/auth/logout (clears cookie, idempotent)
- SetupRedirectMiddleware: 307 → /api/setup for all API paths until setup done
- require_auth dependency: cookie or Bearer token → Session or 401
- conftest.py: manually bootstraps app.state.db for router tests
  (ASGITransport does not trigger ASGI lifespan)
- 85 tests pass; ruff 0 errors; mypy --strict 0 errors

Frontend (tasks 2.7–2.9):
- types/auth.ts, types/setup.ts, api/auth.ts, api/setup.ts
- AuthProvider: sessionStorage-backed context (isAuthenticated, login, logout)
- RequireAuth: guard component → /login?next=<path> when unauthenticated
- SetupPage: Fluent UI form, client-side validation, inline errors
- LoginPage: single password input, ?next= redirect after success
- DashboardPage: placeholder (full impl Stage 5)
- App.tsx: full route tree (/setup, /login, /, *)

frontend/src/api/setup.ts

@@ -0,0 +1,32 @@
+/**
+ * Setup wizard API functions.
+ *
+ * Wraps calls to GET /api/setup and POST /api/setup.
+ */
+
+import { api } from "./client";
+import { ENDPOINTS } from "./endpoints";
+import type {
+  SetupRequest,
+  SetupResponse,
+  SetupStatusResponse,
+} from "../types/setup";
+
+/**
+ * Check whether the initial setup has been completed.
+ *
+ * @returns Setup status response with a `completed` boolean.
+ */
+export async function getSetupStatus(): Promise<SetupStatusResponse> {
+  return api.get<SetupStatusResponse>(ENDPOINTS.setup);
+}
+
+/**
+ * Submit the initial setup configuration.
+ *
+ * @param data - Setup request payload.
+ * @returns Success message from the API.
+ */
+export async function submitSetup(data: SetupRequest): Promise<SetupResponse> {
+  return api.post<SetupResponse>(ENDPOINTS.setup, data);
+}