Phase 2: Visibility Filter & Owner ID

- Add OwnedMixin to 15 models (contact_folder, user_preference, workspace,
  mcp_server_config, agent_definition, automation_definition, report_template,
  report_instance, entity_link, comm_conversation, proactive_suggestion,
  ai_agent, ai_chat_session, tag, share_link)
- Migration 0102: Add owner_id column to 15 tables with backfill from user_id
- Fix EntityPermission Registry: remove notification, add entity_attachment,
  entity_history, subtask, calendar, folder; fix wrong class names
  (DmsFile→File, CalendarEvent→CalendarEntry, Mailbox→MailAccount)
- Add apply_visibility_filter to list endpoints in tags, tasks, mcp_client,
  automation, report_generator, ai_assistant routes
- Add owner_id to create handlers for all new OwnedMixin models
- Patch tasks/services.py and automation/services.py list methods with
  user_id and is_system_admin parameters

app/plugins/builtins/kommunikation/services.py

@@ -258,6 +258,7 @@ async def create_conversation(
     conv = CommConversation(
         tenant_id=tenant_id,
         title=title,
+        owner_id=user_id,
         is_direct=is_direct,
         created_by=user_id,
         created_by_type="user",
@@ -1068,6 +1069,7 @@ async def create_plugin_room(
     conv = CommConversation(
         tenant_id=tenant_id,
         title=title,
+        owner_id=user_id,
         is_locked=True,
         locked_by=plugin_name,
         is_direct=False,