feat(ui): integrate login with shared auth shell

docs/tests/web/account-shell-integration.md

@@ -8,15 +8,15 @@
 
 ## Protected behavior
 
-The authenticated account-creation page consumes the shared role-aware desktop shell and posts to the real account endpoint. The public activation page consumes the local themed authentication shell while preserving its single-use raw-token form contract. The Admin dashboard and navigation link to the implemented `/admin/accounts/new` route.
+The authenticated account-creation page consumes the shared role-aware desktop shell and posts to the real account endpoint. The public activation and login pages consume the local themed authentication shell while preserving their raw-token and Spring Security form contracts. The Admin dashboard and navigation link to the implemented `/admin/accounts/new` route, and logout remains a CSRF-protected POST in the shared shell.
 
 ## Test method
 
-A focused MockMvc slice renders both production account templates through a test-only controller. It asserts the authenticated and public shell markers, local pre-paint theme and CSS assets, real form actions, activation token retention, and the real account-creation URL. The existing PostgreSQL Account web flow then exercises account creation, activation, authentication, authorization, and logout through the production controller and services.
+A focused MockMvc slice renders the production account-creation, activation, and login templates through a test-only controller. It asserts the authenticated and public shell markers, local pre-paint theme and CSS assets, real form actions, accessible error status, activation token retention, and the real account-creation URL. The existing PostgreSQL Account and Authentication web flows then exercise account creation, activation, normalized login, failed login, authorization, and logout through the production controllers and services.
 
 ## Hand-derived expected result
 
-The account-creation response contains `app-shell`, posts to `/admin/accounts`, and exposes `/admin/accounts/new` as the account navigation target. The activation response contains `auth-shell`, posts to `/activate`, retains `raw-token`, and loads `/assets/theme.js` before `/assets/app.css`. Existing account lifecycle and Admin dashboard requests remain successful on PostgreSQL.
+The account-creation response contains `app-shell`, posts to `/admin/accounts`, and exposes `/admin/accounts/new` as the account navigation target. The activation response contains `auth-shell`, posts to `/activate`, retains `raw-token`, and loads `/assets/theme.js` before `/assets/app.css`. Login contains `auth-shell`, posts the expected `username` and `password` fields to `/login`, and exposes a live error announcement. Existing account lifecycle and Admin dashboard requests remain successful on PostgreSQL.
 
 ## RED
 
@@ -38,7 +38,16 @@ BUILD FAILURE
 Total time: 4.763 s
 ```
 
-Both production templates were standalone documents and did not consume either shared layout.
+The account-creation and activation templates were standalone documents and did not consume either shared layout.
+
+After the custom login page landed, its focused pre-change contract also failed as expected:
+
+```text
+Tests run: 1, Failures: 1, Errors: 0, Skipped: 0
+AccountTemplateIntegrationTest.loginUsesPublicAuthShellAndPreservesAuthenticationContract expected class="auth-shell"
+BUILD FAILURE
+Total time: 5.343 s
+```
 
 ## GREEN
 
@@ -66,12 +75,12 @@ Total time: 3.710 s
 export JAVA_HOME=/opt/homebrew/opt/openjdk@25
 export PATH="/opt/homebrew/opt/node@24/bin:$JAVA_HOME/bin:$PATH"
 export DOCKER_HOST=unix:///Users/sechmachine/.orbstack/run/docker.sock
-./mvnw -Dtest=AccountWebIntegrationTest,AdminDashboardWebTest test
+./mvnw -Dtest=AccountTemplateIntegrationTest,AuthenticationWebIntegrationTest,AccountWebIntegrationTest test
 
 PostgreSQL 18.4
-Tests run: 4, Failures: 0, Errors: 0, Skipped: 0
+Tests run: 5, Failures: 0, Errors: 0, Skipped: 0
 BUILD SUCCESS
-Total time: 12.219 s
+Total time: 18.361 s
 ```
 
 ## External-test boundaries

src/main/resources/templates/accounts/login.html

@@ -1,18 +1,19 @@
 <!doctype html>
-<html lang="en" xmlns:th="http://www.thymeleaf.org">
-<head><meta charset="utf-8"><title>Sign in · Lab Timesheet</title></head>
+<html lang="en" xmlns:th="http://www.thymeleaf.org"
+      th:replace="~{fragments/auth-layout :: shell(
+          pageTitle='Sign in',
+          eyebrow='Lab Timesheet',
+          content=~{::main})}">
 <body>
 <main>
-  <h1>Sign in</h1>
-  <p th:if="${param.error}">Invalid email or password</p>
-  <p th:if="${param.logout}">You have signed out</p>
-  <p th:if="${param.activated}">Your account is active. Sign in to continue.</p>
-  <form method="post" th:action="@{/login}">
-    <label for="username">Email</label>
-    <input id="username" name="username" type="email" autocomplete="username" required autofocus>
-    <label for="password">Password</label>
-    <input id="password" name="password" type="password" autocomplete="current-password" required>
-    <button type="submit">Sign in</button>
+  <p class="page-description">Use the email address and password associated with your active account.</p>
+  <p class="alert alert-error" th:if="${param.error}" role="alert">Invalid email or password</p>
+  <p class="alert" th:if="${param.logout}" role="status">You have signed out</p>
+  <p class="alert" th:if="${param.activated}" role="status">Your account is active. Sign in to continue.</p>
+  <form class="form-grid auth-form" method="post" th:action="@{/login}">
+    <div class="field"><label class="field-label" for="username">Email</label><input class="control" id="username" name="username" type="email" autocomplete="username" required autofocus></div>
+    <div class="field"><label class="field-label" for="password">Password</label><input class="control" id="password" name="password" type="password" autocomplete="current-password" required></div>
+    <button class="button button-primary" type="submit">Sign in</button>
   </form>
 </main>
 </body>

src/test/java/com/lab/labtimesheet/feature/reporting/controller/AccountTemplateIntegrationTest.java

@@ -49,6 +49,20 @@ class AccountTemplateIntegrationTest {
                 .andExpect(content().string(containsString("href=\"/assets/app.css\"")));
     }
 
+    @Test
+    void loginUsesPublicAuthShellAndPreservesAuthenticationContract() throws Exception {
+        mvc.perform(get("/template-contract/accounts/login")
+                        .param("error", "")
+                        .with(user("anonymous-template-viewer")))
+                .andExpect(status().isOk())
+                .andExpect(content().string(containsString("class=\"auth-shell\"")))
+                .andExpect(content().string(containsString("action=\"/login\"")))
+                .andExpect(content().string(containsString("name=\"username\"")))
+                .andExpect(content().string(containsString("autocomplete=\"current-password\"")))
+                .andExpect(content().string(containsString("role=\"alert\"")))
+                .andExpect(content().string(containsString("src=\"/assets/theme.js\"")));
+    }
+
     @Controller
     public static class TemplateController {
 
@@ -62,5 +76,10 @@ class AccountTemplateIntegrationTest {
             model.addAttribute("token", "raw-token");
             return "accounts/activate";
         }
+
+        @GetMapping("/template-contract/accounts/login")
+        String login() {
+            return "accounts/login";
+        }
     }
 }