ui: minimalist /f/[slug] polish

- Drop the inline-label name row (.fb-name-row) — the only
  inline-label-with-input pattern in the app. Replace with the same
  stacked-label .fb-question pattern every other field uses.
- Closed-state: switch from amber .fb-banner--closed to a quiet neutral
  .fb-closed-line (italic muted text between two thin border lines).
  Closed is a state, not an alert.
- Mine-post chat bubble: drop the full primary-coloured border in favour
  of a 3px left-border-only accent. Less loud, still recognisable.
- Footer "fdbck.msbls.de" wraps as a permalink to / with hover affordance.

German strings on this page are unchanged per m's override (m/fdbck#3
will handle proper i18n separately).

src/lib/styles/feedback.css

@@ -475,7 +475,8 @@ body { min-height: 100vh; }
 
 .fb-chat__post--mine {
 	background: var(--color-primary-light);
-	border-color: var(--color-primary);
+	border-color: var(--color-border-primary);
+	border-left: 3px solid var(--color-primary);
 }
 
 .fb-chat__post--hidden {

src/routes/f/[slug]/+page.svelte

@@ -303,14 +303,14 @@
 	</header>
 
 	{#if isClosed || chatStatus === 'closed'}
-		<div class="fb-banner fb-banner--closed">
+		<div class="fb-closed-line">
 			Diese Feedback-Sitzung ist geschlossen — neue Beiträge sind nicht mehr möglich.
 		</div>
 	{/if}
 
-	<div class="fb-section">
-		<div class="fb-name-row">
-			<label for="fb-name">Dein Name (optional):</label>
+	<section class="fb-section">
+		<div class="fb-question">
+			<label class="fb-question__label" for="fb-name">Dein Name (optional)</label>
 			<input
 				id="fb-name"
 				type="text"
@@ -321,7 +321,7 @@
 				oninput={saveName}
 			/>
 		</div>
-	</div>
+	</section>
 
 	{#if chatEnabled}
 		<section class="fb-section" aria-label="Live-Chat">
@@ -543,5 +543,15 @@
 		</section>
 	{/if}
 
-	<div class="fb-foot">fdbck.msbls.de</div>
+	<div class="fb-foot"><a href="/" class="fb-foot__link">fdbck.msbls.de</a></div>
 </div>
+
+<style>
+	.fb-foot__link {
+		color: inherit;
+		text-decoration: none;
+	}
+	.fb-foot__link:hover {
+		color: var(--color-text-primary);
+	}
+</style>