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/entity_links/routes.py

@@ -9,6 +9,7 @@ from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.core.db import get_db
+from app.core.visibility import apply_visibility_filter
 from app.deps import get_current_user, require_permission
 from app.plugins.builtins.entity_links.models import EntityLink
 from app.plugins.builtins.entity_links.schemas import EntityLinkRequest
@@ -92,6 +93,7 @@ async def unlink_file_from_entity(
 ):
     """Remove a link between a file and an entity."""
     tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
     fid = _parse_uuid(file_id, "file_id")
     entity_id = _parse_uuid(body.entity_id, "entity_id")
 
@@ -119,6 +121,7 @@ async def list_file_links(
 ):
     """List all entities linked to a file."""
     tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
     fid = _parse_uuid(file_id, "file_id")
 
     result = await db.execute(