fix: Set is_placeholder=False in processor to fix search filtering

The processor was not setting is_placeholder field when writing real
document chunks to Qdrant. This caused the placeholder filter to exclude
all documents (since None != False), resulting in 0 search results.

Now explicitly sets is_placeholder: False in payload when writing real
indexed chunks, allowing search filters to correctly distinguish between
placeholders and real documents.

nextcloud_mcp_server/observability/logging_config.py

@@ -37,19 +37,18 @@ class HealthCheckFilter(logging.Filter):
         """
         # Check if the log message contains health check endpoints
         message = record.getMessage()
-        return (
-            not any(
-                endpoint in message
-                for endpoint in [
-                    "/health/live",
-                    "/health/ready",
-                    "/metrics",
-                    "/app/vector-sync/status",
-                ]
-            )
-            or "OpenCV not installed. Disabling OCR" in message
+        health_check = any(
+            endpoint in message
+            for endpoint in [
+                "/health/live",
+                "/health/ready",
+                "/metrics",
+                "/app/vector-sync/status",
+            ]
         )
 
+        return not health_check
+
 
 class TraceContextFormatter(JsonFormatter):
     """