feat: expert mode + stage outputs in value table (Issue #47)

FEATURE: Experten-Modus 🔬
- Toggle-Button in Wertetabelle
- Normal: Nur gefüllte Werte anzeigen
- Experten: Alle Platzhalter inkl. leere/technische
- Anzeige: "(+X ausgeblendet)" wenn Werte gefiltert
- Button-Style: Accent wenn aktiv

FILTER: Leere Werte ausblenden (Normal-Modus)
- Filtert: '', 'nicht verfügbar', '[Nicht verfügbar]'
- Zeigt nur relevante Nutzer-Daten
- Experten-Modus zeigt alles

FEATURE: Stage-Outputs in Wertetabelle ✅
ROOT CAUSE: stage_N_key Platzhalter hatten keine Werte
- Stage-Outputs (z.B. stage_1_body) sind Basis-Analysen-Ergebnisse
- Wurden nicht in cleaned_values gefunden (nur statische Platzhalter)
FIX:
- Collect stage outputs aus result.debug.stages[].output
- Store als stage_N_key dict
- Lookup: erst stage_outputs, dann cleaned_values
- Description: "Output aus Stage X (Basis-Analyse)"
- JSON-Werte automatisch serialisiert

BEISPIEL Pipeline-Wertetabelle:
┌──────────────────────────────────────────────┐
│ 📊 Verwendete Werte (8) (+3 ausgeblendet) 🔬│
│ ┌──────────────────────────────────────────┐ │
│ │ weight_aktuell  │ 85.2 kg   │ Gewicht  │ │
│ │ stage_1_body    │ {"bmi":...│ Output...│ │ ← Stage output!
│ │ stage_1_nutr... │ {"kcal"...│ Output...│ │
│ └──────────────────────────────────────────┘ │
└──────────────────────────────────────────────┘

AKTIVIERUNG Experten-Modus:
1. Analyse öffnen
2. "📊 Verwendete Werte" aufklappen
3. Button "🔬 Experten-Modus" klicken
4. Zeigt alle Platzhalter (auch leere stage outputs)

version: 9.8.0 (feature)
module: prompts 2.3.0, insights 1.6.0

backend/routers/prompts.py

@@ -856,6 +856,19 @@ async def execute_unified_prompt(
             elif result['type'] == 'pipeline':
                 # Pipeline: collect from all stages
                 stages_debug = result['debug'].get('stages', [])
+
+                # First, collect stage outputs (outputs from base prompts in each stage)
+                stage_outputs = {}
+                for stage_debug in stages_debug:
+                    stage_num = stage_debug.get('stage', 0)
+                    stage_output = stage_debug.get('output', {})
+                    if isinstance(stage_output, dict):
+                        for output_key, output_value in stage_output.items():
+                            # Store stage outputs (e.g., stage_1_body)
+                            placeholder_key = f"stage_{stage_num}_{output_key}"
+                            stage_outputs[placeholder_key] = output_value
+
+                # Collect all resolved placeholders from prompts
                 for stage_debug in stages_debug:
                     for prompt_debug in stage_debug.get('prompts', []):
                         resolved_keys = []
@@ -867,9 +880,13 @@ async def execute_unified_prompt(
 
                         for key in resolved_keys:
                             if key not in metadata['placeholders']:  # Avoid duplicates
-                                # Get full untruncated value
-                                value = cleaned_values.get(key, '')
+                                # Get value: first try stage outputs, then cleaned_values
+                                value = stage_outputs.get(key, cleaned_values.get(key, ''))
 
+                                # For stage output placeholders, add special description
+                                if key.startswith('stage_'):
+                                    desc = f"Output aus Stage {key.split('_')[1]} (Basis-Analyse)"
+                                else:
                                     # Find description in catalog
                                     desc = None
                                     for cat_items in catalog.values():
@@ -877,10 +894,11 @@ async def execute_unified_prompt(
                                         if matching:
                                             desc = matching[0].get('description', '')
                                             break
+                                    desc = desc or ''
 
                                 metadata['placeholders'][key] = {
-                                    'value': value,
-                                    'description': desc or ''
+                                    'value': value if isinstance(value, str) else json.dumps(value, ensure_ascii=False),
+                                    'description': desc
                                 }
 
         # Save to database with metadata

frontend/src/pages/Analysis.jsx

@@ -24,6 +24,7 @@ function InsightCard({ ins, onDelete, defaultOpen=false, prompts=[] }) {
   const showOnlyValues = isBasePrompt && isJsonOutput && Object.keys(placeholdersRaw).length > 0
 
   const [showValues, setShowValues] = useState(showOnlyValues) // Auto-expand for base prompts with JSON
+  const [expertMode, setExpertMode] = useState(false) // Show empty/technical placeholders
 
   // Find matching prompt to get display_name
   const prompt = prompts.find(p => p.slug === ins.scope)
@@ -31,8 +32,20 @@ function InsightCard({ ins, onDelete, defaultOpen=false, prompts=[] }) {
 
   // Use already-parsed metadata
   const metadata = metadataRaw
-  const placeholders = placeholdersRaw
+  const allPlaceholders = placeholdersRaw
+
+  // Filter placeholders: In normal mode, hide empty values
+  const placeholders = expertMode
+    ? allPlaceholders
+    : Object.fromEntries(
+        Object.entries(allPlaceholders).filter(([key, data]) => {
+          const val = data.value || ''
+          return val.trim() !== '' && val !== 'nicht verfügbar' && val !== '[Nicht verfügbar]'
+        })
+      )
+
   const placeholderCount = Object.keys(placeholders).length
+  const hiddenCount = Object.keys(allPlaceholders).length - placeholderCount
 
   return (
     <div className="card section-gap" style={{borderLeft:`3px solid var(--accent)`}}>
@@ -83,6 +96,7 @@ function InsightCard({ ins, onDelete, defaultOpen=false, prompts=[] }) {
           {/* Value Table */}
           {placeholderCount > 0 && (
             <div style={{ marginTop: 16, borderTop: '1px solid var(--border)', paddingTop: 12 }}>
+              <div style={{ display: 'flex', alignItems: 'center', justifyContent: 'space-between' }}>
                 <div
                   onClick={() => setShowValues(!showValues)}
                   style={{
@@ -97,6 +111,30 @@ function InsightCard({ ins, onDelete, defaultOpen=false, prompts=[] }) {
                 >
                   {showValues ? <ChevronUp size={14} /> : <ChevronDown size={14} />}
                   📊 Verwendete Werte ({placeholderCount})
+                  {hiddenCount > 0 && !expertMode && (
+                    <span style={{ fontSize: 10, color: 'var(--text3)', fontWeight: 400 }}>
+                      (+{hiddenCount} ausgeblendet)
+                    </span>
+                  )}
+                </div>
+
+                {showValues && Object.keys(allPlaceholders).length > 0 && (
+                  <button
+                    onClick={(e) => {
+                      e.stopPropagation()
+                      setExpertMode(!expertMode)
+                    }}
+                    className="btn"
+                    style={{
+                      fontSize: 10,
+                      padding: '4px 8px',
+                      background: expertMode ? 'var(--accent)' : 'var(--surface)',
+                      color: expertMode ? 'white' : 'var(--text2)'
+                    }}
+                  >
+                    🔬 Experten-Modus
+                  </button>
+                )}
               </div>
 
               {showValues && (