feat(a11y): fix heading hierarchy across pages

- Home: greeting H2 → H1 (page needs a top-level heading)
- Task detail: task ID H1 → span (only title should be H1)
- Task detail: H6 breadcrumb → nav element
- App header: project title H1 → span (avoids duplicate H1)

Fixes WCAG 1.3.1 (Info and Relationships) and 2.4.6 (Headings).

frontend/src/components/home/AppHeader.vue

@@ -21,9 +21,9 @@
 			v-if="currentProject?.id"
 			class="project-title-wrapper"
 		>
-			<h1 class="project-title">
+			<span class="project-title">
 				{{ currentProject.title === '' ? $t('misc.loading') : getProjectTitle(currentProject) }}
-			</h1>
+			</span>
 
 			<BaseButton
 				v-if="!isEditorContentEmpty(currentProject.description)"

frontend/src/components/tasks/partials/Heading.vue

@@ -7,9 +7,9 @@
 					:color="getHexColor(task.hexColor)"
 				/>
 				<BaseButton @click="copyUrl">
-					<h1 class="title task-id">
+					<span class="title task-id">
 						{{ textIdentifier }}
-					</h1>
+					</span>
 				</BaseButton>
 			</div>
 			<Done

frontend/src/views/Home.vue

@@ -1,8 +1,8 @@
 <template>
 	<div class="content has-text-centered">
-		<h2 v-if="salutation">
+		<h1 v-if="salutation">
 			{{ salutation }}
-		</h2>
+		</h1>
 
 		<Message
 			v-if="deletionScheduledAt !== null"

frontend/src/views/tasks/TaskDetailView.vue

@@ -28,8 +28,9 @@
 				@update:task="Object.assign(task, $event)"
 				@close="$emit('close')"
 			/>
-			<h6
+			<nav
 				v-if="project?.id"
+				aria-label="Breadcrumb"
 				class="subtitle"
 			>
 				<template
@@ -60,7 +61,7 @@
 					:can-write="canWrite"
 					@update:task="Object.assign(task, $event)"
 				/>
-			</h6>
+			</nav>
 
 			<ChecklistSummary :task="task" />
 

frontend/tests/e2e/task/task.spec.ts

@@ -278,8 +278,8 @@ test.describe('Task', () => {
 			await page.goto(`/tasks/${tasks[0].id}`)
 
 			await expect(page.locator('.task-view h1.title.input')).toContainText(tasks[0].title)
-			await expect(page.locator('.task-view h1.title.task-id')).toContainText('#1')
-			await expect(page.locator('.task-view h6.subtitle')).toContainText(projects[0].title)
+			await expect(page.locator('.task-view span.title.task-id')).toContainText('#1')
+			await expect(page.locator('.task-view nav.subtitle')).toContainText(projects[0].title)
 			await expect(page.locator('.task-view .details.content.description')).toContainText(tasks[0].description)
 			await expect(page.locator('.task-view .action-buttons p.created')).toContainText('Created')
 		})
@@ -328,7 +328,7 @@ test.describe('Task', () => {
 
 			await page.goto(`/tasks/${tasks[0].id}`)
 
-			await expect(page.locator('.task-view h1.title.task-id')).toContainText(`${projects[0].identifier}-${tasks[0].index}`)
+			await expect(page.locator('.task-view span.title.task-id')).toContainText(`${projects[0].identifier}-${tasks[0].index}`)
 		})
 
 		test('Can edit the description', async ({authenticatedPage: page}) => {
@@ -367,7 +367,7 @@ test.describe('Task', () => {
 			await page.locator('.task-view .details.content.description .tiptap button.done-edit', {timeout: 30_000}).click()
 			await page.locator('.task-view .details.content.description .tiptap__editor .tiptap.ProseMirror').fill('New Description')
 
-			await page.locator('.task-view h6.subtitle a').first().click()
+			await page.locator('.task-view nav.subtitle a').first().click()
 
 			await page.goto('/tasks/1')
 			await expect(page.locator('.task-view .details.content.description')).toContainText('New Description')
@@ -443,7 +443,7 @@ test.describe('Task', () => {
 			await expect(page.locator('.task-view .content.details .field .multiselect.control .search-results')).toBeVisible({timeout: 5000})
 			await page.locator('.task-view .content.details .field .multiselect.control .search-results').locator('> *').first().click()
 
-			await expect(page.locator('.task-view h6.subtitle')).toContainText(projects[1].title)
+			await expect(page.locator('.task-view nav.subtitle')).toContainText(projects[1].title)
 			await expect(page.locator('.global-notification')).toContainText('Success')
 		})
 

frontend/tests/e2e/user/login.spec.ts

@@ -45,7 +45,7 @@ test.describe('Login', () => {
 	test('Should log in with the right credentials', async ({page}) => {
 		await page.goto('/login')
 		await login(page)
-		await expect(page.locator('main h2')).toContainText(credentials.username)
+		await expect(page.locator('main h1')).toContainText(credentials.username)
 	})
 
 	test('Should fail with a bad password', async ({page}) => {

frontend/tests/e2e/user/openid-login.spec.ts

@@ -15,7 +15,7 @@ test.describe('OpenID Login', () => {
 
 		// Should redirect back to the app
 		await expect(page).toHaveURL(/\//)
-		await expect(page.locator('main.app-content .content h2')).toContainText('test')
+		await expect(page.locator('main.app-content .content h1')).toContainText('test')
 		await expect(page.locator('.show-tasks h3')).toContainText('Current Tasks')
 	})
 })

frontend/tests/e2e/user/registration.spec.ts

@@ -27,7 +27,7 @@ test.describe('Registration', () => {
 		await page.locator('#password').fill(fixture.password)
 		await page.locator('#register-submit').click()
 		await expect(page).toHaveURL('/')
-		await expect(page.locator('main h2')).toContainText(fixture.username)
+		await expect(page.locator('main h1')).toContainText(fixture.username)
 	})
 
 	test('Should fail', async ({page, apiContext}) => {

frontend/tests/e2e/user/session-refresh.spec.ts

@@ -11,7 +11,7 @@ async function loginViaBrowser(page, username: string) {
 	await page.locator('input[id=password]').fill(TEST_PASSWORD)
 	await page.locator('.button').filter({hasText: 'Login'}).click()
 	await expect(page).toHaveURL('/')
-	await expect(page.locator('main h2')).toContainText(username)
+	await expect(page.locator('main h1')).toContainText(username)
 
 	// Wait for the proactive refresh (from useRenewTokenOnFocus) to complete
 	// so it doesn't race with our test assertions.