fix: resolve design token violations and locale bug

- Add --color-warning-translucent and --color-soon tokens to tokens.css
- Replace hardcoded font-size 1.4rem with var(--text-xl) in dashboard.css
- Replace hardcoded rgba color with var(--color-warning-translucent)
- Remove duplicate .task-item__meta--overdue rule
- Fix hardcoded 'de-DE' locale: use formatTime() from i18n.js
- Fix formatDueDate: don't show time (23:59) when no due_time is set

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

public/pages/dashboard.js

@@ -96,7 +96,7 @@ function formatDueDate(dateStr, timeStr) {
   }
 
   if (calDayDiff === 0) {
-    return { text: `${t('dashboard.dueToday')} – ${formatTime(dueDate)}`, overdue: false, soon: true };
+    return { text: timeStr ? `${t('dashboard.dueToday')} – ${formatTime(dueDate)}` : t('dashboard.dueToday'), overdue: false, soon: true };
   }
 
   if (calDayDiff === 1) {
@@ -195,7 +195,7 @@ function renderGreeting(user, stats = {}) {
       ${t('dashboard.todayMealChip', { title: esc(todayMealTitle) })}
     </span>`);
 
-  let time = new Date().toLocaleTimeString('de-DE', { hour: '2-digit', minute: '2-digit' });
+  const time = formatTime(new Date());
 
   return `
     <div class="widget-greeting">

public/styles/dashboard.css

@@ -118,7 +118,7 @@
 
 @media (min-width: 1024px) {
   .widget-greeting__title {
-    font-size: 1.4rem;
+    font-size: var(--text-xl);
     opacity: 0.85;
     white-space: nowrap;
     padding-top: 4px;
@@ -155,7 +155,7 @@
 }
 
 .greeting-chip--due {
-  background: rgba(245, 158, 11, 0.28);
+  background: var(--color-warning-translucent);
 }
 
 /* --------------------------------------------------------
@@ -341,11 +341,6 @@
   font-weight: var(--font-weight-medium);
 }
 
-.task-item__meta--overdue {
-  color: var(--color-danger);
-  font-weight: var(--font-weight-medium);
-}
-
 .task-item__avatar {
   width: var(--space-5);
   height: var(--space-5);

public/styles/tokens.css

@@ -221,6 +221,8 @@
   --color-glass-hover: rgba(255, 255, 255, 0.3);
   --color-glass-border: rgba(255, 255, 255, 0.15);
   --color-danger-translucent:  rgba(255, 59, 48, 0.35);
+  --color-warning-translucent: rgba(245, 158, 11, 0.28);
+  --color-soon: var(--color-warning);
 
   /* --------------------------------------------------------
    * 8. Schatten