fix: Workflow placeholder resolution + complete catalog display

Backend workflow_executor.py:
- load_prompt_template() now uses modern resolve_placeholders() from prompt_executor
- Calls get_placeholder_example_values() to populate ALL registered placeholders
- Passes catalog for |d modifier support
- Fixes issue where basis prompts had empty/null placeholder values in workflows

Backend placeholder_resolver.py:
- get_placeholder_catalog() now includes ALL placeholders from PLACEHOLDER_MAP
- Uncategorized placeholders added to "Sonstiges" category
- Fixes discrepancy: 111 total placeholders but only ~30 shown in picker

Root Cause:
- Workflow used old resolve_placeholders() (only PLACEHOLDER_MAP, no variables)
- Isolated execution used modern resolve_placeholders() (full variables dict)
- Catalog excluded non-registry placeholders from PLACEHOLDER_MAP

Impact:
- All placeholders now resolve correctly in workflow execution
- PlaceholderPicker shows all 111+ placeholders (not just registry ones)

Version: 0.9p (workflow module)
Part 3: End Node Template Engine - Bug Fixes

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

backend/placeholder_resolver.py

@@ -1470,4 +1470,33 @@ def get_placeholder_catalog(profile_id: str) -> Dict[str, List[Dict[str, str]]]:
                 'example': str(example)
             })
 
+    # Add ALL remaining placeholders from PLACEHOLDER_MAP that aren't categorized yet
+    # This ensures PlaceholderPicker shows all 111+ placeholders, not just registry ones
+    all_categorized_keys = set()
+    for items in catalog.values():
+        all_categorized_keys.update(p['key'] for p in items)
+
+    sonstige_category = 'Sonstiges'
+    if sonstige_category not in catalog:
+        catalog[sonstige_category] = []
+
+    for placeholder, resolver in PLACEHOLDER_MAP.items():
+        # Extract key from {{key}}
+        key = placeholder.replace('{{', '').replace('}}', '')
+
+        # Skip if already categorized
+        if key in all_categorized_keys:
+            continue
+
+        try:
+            example = resolver(profile_id)
+        except Exception:
+            example = '[Nicht verfügbar]'
+
+        catalog[sonstige_category].append({
+            'key': key,
+            'description': f'Platzhalter: {key}',  # Generic description
+            'example': str(example)
+        })
+
     return catalog

backend/workflow_executor.py

@@ -766,7 +766,8 @@ async def load_prompt_template(prompt_slug: str, context: Dict[str, Any]) -> str
         >>> "{{name}}" not in template
         True
     """
-    from placeholder_resolver import resolve_placeholders
+    from placeholder_resolver import get_placeholder_example_values, get_placeholder_catalog
+    from prompt_executor import resolve_placeholders
 
     with get_db() as conn:
         cur = get_cursor(conn)
@@ -780,13 +781,37 @@ async def load_prompt_template(prompt_slug: str, context: Dict[str, Any]) -> str
 
         template = row['template']
 
-    # Resolve Placeholders
+    # Resolve Placeholders using modern prompt_executor method
     profile_id = context.get("profile_id")
+
+    # Build variables dict with ALL registered placeholders
+    variables = {}
+
+    try:
+        # Get all placeholder values from registry
+        processed_placeholders = get_placeholder_example_values(profile_id)
+        # Remove {{ }} from keys (placeholder_resolver returns them with wrappers)
+        cleaned_placeholders = {
+            key.replace('{{', '').replace('}}', ''): value
+            for key, value in processed_placeholders.items()
+        }
+        variables.update(cleaned_placeholders)
+    except Exception as e:
+        logger.warning(f"Failed to load placeholders for workflow: {e}")
+
+    # Load catalog for |d modifier support
+    try:
+        catalog = get_placeholder_catalog(profile_id)
+    except Exception as e:
+        catalog = None
+        logger.warning(f"Failed to load placeholder catalog for workflow: {e}")
+
+    # Resolve with modern executor
     resolved = resolve_placeholders(
         template=template,
-        profile_id=profile_id
+        variables=variables,
+        catalog=catalog
     )
-    # TODO Phase 3: Support custom variables from workflow context
 
     return resolved