feat: dashboard rest days widget + today highlighting

- Add RestDaysWidget component showing today's rest days with icons & colors
- Integrate widget into Dashboard (above training distribution)
- Highlight current day in RestDaysPage (accent border + HEUTE badge)
- Fix: Improve error handling in api.js (parse JSON detail field)

Part of v9d Phase 2 (Vitals & Recovery)

frontend/src/components/RestDaysWidget.jsx

@@ -0,0 +1,120 @@
+import { useState, useEffect } from 'react'
+import { useNavigate } from 'react-router-dom'
+import { api } from '../utils/api'
+import dayjs from 'dayjs'
+import 'dayjs/locale/de'
+dayjs.locale('de')
+
+const FOCUS_ICONS = {
+  muscle_recovery: '💪',
+  cardio_recovery: '🏃',
+  mental_rest: '🧘',
+  deload: '📉',
+  injury: '🩹',
+}
+
+const FOCUS_LABELS = {
+  muscle_recovery: 'Muskelregeneration',
+  cardio_recovery: 'Cardio-Erholung',
+  mental_rest: 'Mentale Erholung',
+  deload: 'Deload',
+  injury: 'Verletzungspause',
+}
+
+const FOCUS_COLORS = {
+  muscle_recovery: '#D85A30',
+  cardio_recovery: '#378ADD',
+  mental_rest: '#7B68EE',
+  deload: '#E67E22',
+  injury: '#E74C3C',
+}
+
+export default function RestDaysWidget() {
+  const [todayRestDays, setTodayRestDays] = useState([])
+  const [loading, setLoading] = useState(true)
+  const nav = useNavigate()
+
+  useEffect(() => {
+    loadTodayRestDays()
+  }, [])
+
+  const loadTodayRestDays = async () => {
+    try {
+      const today = dayjs().format('YYYY-MM-DD')
+      const allRestDays = await api.listRestDays(7) // Last 7 days
+      const todayOnly = allRestDays.filter(d => d.date === today)
+      setTodayRestDays(todayOnly)
+    } catch (err) {
+      console.error('Failed to load rest days:', err)
+    } finally {
+      setLoading(false)
+    }
+  }
+
+  if (loading) {
+    return (
+      <div className="card">
+        <div className="card-title">🛌 Ruhetage</div>
+        <div style={{ padding: '20px 0', textAlign: 'center', color: 'var(--text3)' }}>
+          Lädt...
+        </div>
+      </div>
+    )
+  }
+
+  return (
+    <div className="card">
+      <div className="card-title">🛌 Ruhetage</div>
+
+      {todayRestDays.length === 0 ? (
+        <div style={{ padding: '12px 0', color: 'var(--text3)', fontSize: 13 }}>
+          Heute kein Ruhetag geplant
+        </div>
+      ) : (
+        <div style={{ display: 'flex', flexDirection: 'column', gap: 6 }}>
+          {todayRestDays.map(day => {
+            const focus = day.rest_config?.focus || 'mental_rest'
+            const icon = FOCUS_ICONS[focus] || '📅'
+            const label = FOCUS_LABELS[focus] || focus
+            const color = FOCUS_COLORS[focus] || '#888'
+
+            return (
+              <div
+                key={day.id}
+                style={{
+                  display: 'flex',
+                  alignItems: 'center',
+                  gap: 10,
+                  padding: '8px 10px',
+                  borderRadius: 8,
+                  background: `${color}14`,
+                  border: `1px solid ${color}`,
+                }}
+              >
+                <div style={{ fontSize: 20 }}>{icon}</div>
+                <div style={{ flex: 1 }}>
+                  <div style={{ fontSize: 13, fontWeight: 600, color }}>
+                    {label}
+                  </div>
+                  {day.note && (
+                    <div style={{ fontSize: 11, color: 'var(--text3)', marginTop: 2 }}>
+                      {day.note}
+                    </div>
+                  )}
+                </div>
+              </div>
+            )
+          })}
+        </div>
+      )}
+
+      <button
+        className="btn btn-secondary btn-full"
+        style={{ marginTop: 12, fontSize: 13 }}
+        onClick={() => nav('/rest-days')}
+      >
+        Ruhetage verwalten
+      </button>
+    </div>
+  )
+}

frontend/src/pages/Dashboard.jsx

@@ -12,6 +12,7 @@ import TrialBanner from '../components/TrialBanner'
 import EmailVerificationBanner from '../components/EmailVerificationBanner'
 import TrainingTypeDistribution from '../components/TrainingTypeDistribution'
 import SleepWidget from '../components/SleepWidget'
+import RestDaysWidget from '../components/RestDaysWidget'
 import { getInterpretation, getStatusColor, getStatusBg } from '../utils/interpret'
 import Markdown from '../utils/Markdown'
 import dayjs from 'dayjs'
@@ -477,6 +478,11 @@ export default function Dashboard() {
           <SleepWidget/>
         </div>
 
+        {/* Rest Days Widget */}
+        <div style={{marginBottom:16}}>
+          <RestDaysWidget/>
+        </div>
+
         {/* Training Type Distribution */}
         {activities.length > 0 && (
           <div className="card section-gap" style={{marginBottom:16}}>

frontend/src/pages/RestDaysPage.jsx

@@ -356,9 +356,14 @@ export default function RestDaysPage() {
           const isEditing = editing?.id === day.id
           const focus = day.rest_config?.focus || 'mental_rest'
           const preset = PRESETS.find(p => p.id === focus)
+          const isToday = day.date === dayjs().format('YYYY-MM-DD')
 
           return (
-            <div key={day.id} className="card" style={{ marginBottom: 8 }}>
+            <div key={day.id} className="card" style={{
+              marginBottom: 8,
+              border: isToday ? '2px solid var(--accent)' : undefined,
+              background: isToday ? 'var(--accent)08' : undefined,
+            }}>
               {isEditing ? (
                 <div>
                   <div style={{ fontWeight: 600, fontSize: 14, marginBottom: 8 }}>
@@ -399,9 +404,23 @@ export default function RestDaysPage() {
                     alignItems: 'center',
                     marginBottom: 8,
                   }}>
+                    <div style={{ display: 'flex', alignItems: 'center', gap: 8 }}>
                       <div style={{ fontWeight: 600, fontSize: 14 }}>
                         {dayjs(day.date).format('DD. MMMM YYYY')}
                       </div>
+                      {isToday && (
+                        <span style={{
+                          padding: '2px 8px',
+                          borderRadius: 4,
+                          background: 'var(--accent)',
+                          color: 'white',
+                          fontSize: 11,
+                          fontWeight: 600,
+                        }}>
+                          HEUTE
+                        </span>
+                      )}
+                    </div>
                     <div style={{ display: 'flex', gap: 6 }}>
                       <button
                         className="btn btn-secondary"

frontend/src/utils/api.js

@@ -15,7 +15,16 @@ function hdrs(extra={}) {
 
 async function req(path, opts={}) {
   const res = await fetch(BASE+path, {...opts, headers:hdrs(opts.headers||{})})
-  if (!res.ok) { const err=await res.text(); throw new Error(err) }
+  if (!res.ok) {
+    const err = await res.text()
+    // Try to parse JSON error with detail field
+    try {
+      const parsed = JSON.parse(err)
+      throw new Error(parsed.detail || err)
+    } catch {
+      throw new Error(err)
+    }
+  }
   return res.json()
 }
 const json=(d)=>({method:'POST',headers:{'Content-Type':'application/json'},body:JSON.stringify(d)})