Remove client-side SHA-256 pre-hashing from setup and login

The sha256Hex helper used window.crypto.subtle.digest(), which is only
available in a secure context (HTTPS / localhost). In the HTTP Docker
environment crypto.subtle is undefined, causing a TypeError before any
request is sent — the setup and login forms both silently failed with
'An unexpected error occurred'.

Fix: pass raw passwords directly to the API. The backend already applies
bcrypt, which is sufficient. No stored hashes need migration because
setup never completed successfully in the HTTP environment.

* frontend/src/pages/SetupPage.tsx  — remove sha256Hex call
* frontend/src/api/auth.ts          — remove sha256Hex call
* frontend/src/pages/__tests__/SetupPage.test.tsx — drop crypto mock
* frontend/src/utils/crypto.ts      — deleted (no remaining callers)

frontend/src/api/auth.ts

@@ -7,22 +7,16 @@
 
 import { api } from "./client";
 import { ENDPOINTS } from "./endpoints";
-import type { LoginRequest, LoginResponse, LogoutResponse } from "../types/auth";
+import type { LoginResponse, LogoutResponse } from "../types/auth";
-import { sha256Hex } from "../utils/crypto";
 
 /**
  * Authenticate with the master password.
  *
- * The password is SHA-256 hashed client-side before transmission so that
- * the plaintext never leaves the browser.  The backend bcrypt-verifies the
- * received hash against the stored bcrypt(sha256) digest.
- *
  * @param password - The master password entered by the user.
  * @returns The login response containing the session token.
  */
 export async function login(password: string): Promise<LoginResponse> {
-  const body: LoginRequest = { password: await sha256Hex(password) };
+  return api.post<LoginResponse>(ENDPOINTS.authLogin, { password });
-  return api.post<LoginResponse>(ENDPOINTS.authLogin, body);
 }
 
 /**

frontend/src/pages/SetupPage.tsx

@@ -22,7 +22,6 @@ import { useNavigate } from "react-router-dom";
 import type { ChangeEvent, FormEvent } from "react";
 import { ApiError } from "../api/client";
 import { getSetupStatus, submitSetup } from "../api/setup";
-import { sha256Hex } from "../utils/crypto";
 
 // ---------------------------------------------------------------------------
 // Styles
@@ -177,11 +176,8 @@ export function SetupPage(): React.JSX.Element {
 
     setSubmitting(true);
     try {
-      // Hash the password client-side before transmission — the plaintext
-      // never leaves the browser.  The backend bcrypt-hashes the received hash.
-      const hashedPassword = await sha256Hex(values.masterPassword);
       await submitSetup({
-        master_password: hashedPassword,
+        master_password: values.masterPassword,
         database_path: values.databasePath,
         fail2ban_socket: values.fail2banSocket,
         timezone: values.timezone,

frontend/src/pages/__tests__/SetupPage.test.tsx

@@ -10,11 +10,6 @@ vi.mock("../../api/setup", () => ({
   submitSetup: vi.fn(),
 }));
 
-// Mock the crypto utility — we only need it to resolve without testing SHA256.
-vi.mock("../../utils/crypto", () => ({
-  sha256Hex: vi.fn().mockResolvedValue("hashed-password"),
-}));
-
 import { getSetupStatus } from "../../api/setup";
 
 const mockedGetSetupStatus = vi.mocked(getSetupStatus);

frontend/src/utils/crypto.ts

@@ -1,23 +0,0 @@
-/**
- * Client-side cryptography utilities.
- *
- * Uses the browser-native SubtleCrypto API so no third-party bundle is required.
- */
-
-/**
- * Return the SHA-256 hex digest of `input`.
- *
- * Hashing passwords before transmission means the plaintext never leaves the
- * browser, even when HTTPS is not enforced in a development environment.
- * The backend then applies bcrypt on top of the received hash.
- *
- * @param input - The string to hash (e.g. the master password).
- * @returns Lowercase hex-encoded SHA-256 digest.
- */
-export async function sha256Hex(input: string): Promise<string> {
-  const data = new TextEncoder().encode(input);
-  const hashBuffer = await crypto.subtle.digest("SHA-256", data);
-  return Array.from(new Uint8Array(hashBuffer))
-    .map((b) => b.toString(16).padStart(2, "0"))
-    .join("");
-}