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

alembic/versions/0102_add_owner_id_to_phase2_tables.py

@@ -0,0 +1,69 @@
+"""Add owner_id column to Phase 2 tables for row-level ownership.
+
+Adds nullable owner_id (FK → users.id, ON DELETE SET NULL) to tables
+that gained OwnedMixin in Phase 2. For tables that already have a
+non-nullable user_id column, owner_id is backfilled from user_id.
+
+Revision ID: 0102
+"""
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects.postgresql import UUID as PGUUID
+
+revision = "0102"
+down_revision = "0101"
+branch_labels = None
+depends_on = None
+
+# (table_name, has_user_id_to_backfill)
+TABLES = [
+    # Core models
+    ("contact_folders", True),
+    ("user_preferences", True),
+    ("workspaces", False),
+    # Plugin models
+    ("mcp_server_configs", False),
+    ("automation_agent_definitions", False),
+    ("automation_definitions", False),
+    ("report_templates", False),
+    ("report_instances", False),
+    ("entity_links", False),
+    ("comm_conversations", False),
+    ("ai_proactive_suggestions", True),
+    ("ai_agents", False),
+    ("ai_chat_sessions", True),
+    ("tags", False),
+    ("share_links", True),
+]
+
+
+def upgrade() -> None:
+    for table_name, _has_user_id in TABLES:
+        op.add_column(
+            table_name,
+            sa.Column(
+                "owner_id",
+                PGUUID(as_uuid=True),
+                sa.ForeignKey("users.id", ondelete="SET NULL"),
+                nullable=True,
+            ),
+        )
+        op.create_index(
+            f"ix_{table_name}_owner_id",
+            table_name,
+            ["owner_id"],
+        )
+
+    # Backfill owner_id from user_id where available
+    for table_name, has_user_id in TABLES:
+        if has_user_id:
+            op.execute(
+                f"UPDATE {table_name} SET owner_id = user_id WHERE owner_id IS NULL;"
+            )
+
+
+def downgrade() -> None:
+    for table_name, _ in TABLES:
+        op.drop_index(f"ix_{table_name}_owner_id", table_name=table_name)
+        op.drop_column(table_name, "owner_id")