fix(HelpPopover): role=region, 44px touch target, counter-based ID

- role="tooltip" → role="region" + aria-label={label}: tooltip semantics
  are wrong for a click-triggered panel (Nora/Sara)
- expand button to 44×44px with inner visual <span>: WCAG 2.5.8 touch
  target for 60+ transcriber audience (Sara/Leonie)
- replace Math.random() with module-level counter: SSR/hydration mismatch
  when server and client generate different IDs (Felix)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/lib/components/HelpPopover.svelte

@@ -1,3 +1,10 @@
+<script module>
+// Module-level counter produces stable, predictable IDs across SSR + hydration.
+// Math.random() would generate different values server-side vs client-side,
+// causing a hydration mismatch on first render.
+let _counter = 0;
+</script>
+
 <script lang="ts">
 import type { Snippet } from 'svelte';
 
@@ -11,8 +18,9 @@ type Props = {
 
 let { label, placement = 'bottom', children }: Props = $props();
 
+const popoverId = `help-popover-${_counter++}`;
+
 let open = $state(false);
-const popoverId = `help-popover-${Math.random().toString(36).slice(2)}`;
 let triggerEl: HTMLButtonElement | null = $state(null);
 
 function toggle() {
@@ -58,6 +66,10 @@ const placementClass: Record<Placement, string> = {
 </script>
 
 <div class="relative inline-block">
+	<!--
+		Outer button is 44×44px for WCAG 2.5.8 touch-target compliance (our transcriber
+		audience is 60+). The inner <span> carries the visual 20×20px circle.
+	-->
 	<button
 		bind:this={triggerEl}
 		type="button"
@@ -65,15 +77,20 @@ const placementClass: Record<Placement, string> = {
 		aria-expanded={open}
 		aria-controls={popoverId}
 		onclick={toggle}
+		class="flex h-[44px] w-[44px] items-center justify-center"
+	>
+		<span
 			class="flex h-5 w-5 items-center justify-center rounded-full border border-line bg-muted font-sans text-[10px] font-bold text-ink-3 transition-colors hover:border-brand-navy hover:text-brand-navy"
 		>
 			?
+		</span>
 	</button>
 
 	{#if open}
 		<div
 			id={popoverId}
-			role="tooltip"
+			role="region"
+			aria-label={label}
 			class="absolute z-50 w-64 rounded-sm border border-line bg-white p-3 font-sans text-sm text-ink shadow-md {placementClass[placement]}"
 		>
 			{#if children}

frontend/src/lib/components/HelpPopover.svelte.spec.ts

@@ -20,7 +20,7 @@ describe('HelpPopover — initial state', () => {
 		renderPopover();
 		const btn = page.getByRole('button', { name: /Help/ });
 		await expect.element(btn).toHaveAttribute('aria-expanded', 'false');
-		expect(document.querySelector('[role="tooltip"]')).toBeNull();
+		expect(document.querySelector('[role="region"]')).toBeNull();
 	});
 });
 
@@ -30,37 +30,37 @@ describe('HelpPopover — open / close interactions', () => {
 		await page.getByRole('button', { name: /Help/ }).click();
 		const btn = page.getByRole('button', { name: /Help/ });
 		await expect.element(btn).toHaveAttribute('aria-expanded', 'true');
-		expect(document.querySelector('[role="tooltip"]')).not.toBeNull();
+		expect(document.querySelector('[role="region"]')).not.toBeNull();
 	});
 
 	it('closes on Esc key', async () => {
 		renderPopover();
 		await page.getByRole('button', { name: /Help/ }).click();
-		expect(document.querySelector('[role="tooltip"]')).not.toBeNull();
+		expect(document.querySelector('[role="region"]')).not.toBeNull();
 
 		document.dispatchEvent(new KeyboardEvent('keydown', { key: 'Escape', bubbles: true }));
-		await vi.waitFor(() => expect(document.querySelector('[role="tooltip"]')).toBeNull());
+		await vi.waitFor(() => expect(document.querySelector('[role="region"]')).toBeNull());
 	});
 
 	it('closes on outside click', async () => {
 		renderPopover();
 		await page.getByRole('button', { name: /Help/ }).click();
-		expect(document.querySelector('[role="tooltip"]')).not.toBeNull();
+		expect(document.querySelector('[role="region"]')).not.toBeNull();
 
 		document.dispatchEvent(new PointerEvent('pointerdown', { bubbles: true }));
-		await vi.waitFor(() => expect(document.querySelector('[role="tooltip"]')).toBeNull());
+		await vi.waitFor(() => expect(document.querySelector('[role="region"]')).toBeNull());
 	});
 
 	it('opens on Enter key (button is keyboard-reachable, Enter fires click)', async () => {
 		renderPopover();
 		await page.getByRole('button', { name: /Help/ }).click();
-		expect(document.querySelector('[role="tooltip"]')).not.toBeNull();
+		expect(document.querySelector('[role="region"]')).not.toBeNull();
 	});
 
 	it('opens on Space key (button is keyboard-reachable, Space fires click)', async () => {
 		renderPopover();
 		await page.getByRole('button', { name: /Help/ }).click();
-		expect(document.querySelector('[role="tooltip"]')).not.toBeNull();
+		expect(document.querySelector('[role="region"]')).not.toBeNull();
 	});
 });
 
@@ -74,4 +74,17 @@ describe('HelpPopover — aria wiring', () => {
 		const popover = document.getElementById(controls!);
 		expect(popover).not.toBeNull();
 	});
+
+	it('two renders produce different, predictable IDs (no Math.random — SSR safe)', async () => {
+		const { container: c1 } = render(HelpPopover, { props: { label: 'A' } });
+		const { container: c2 } = render(HelpPopover, { props: { label: 'B' } });
+		const id1 = c1.querySelector('button[aria-controls]')?.getAttribute('aria-controls');
+		const id2 = c2.querySelector('button[aria-controls]')?.getAttribute('aria-controls');
+		expect(id1).toBeTruthy();
+		expect(id2).toBeTruthy();
+		expect(id1).not.toBe(id2);
+		// IDs must be deterministic (counter-based), not random hex
+		expect(id1).toMatch(/^help-popover-\d+$/);
+		expect(id2).toMatch(/^help-popover-\d+$/);
+	});
 });