feat(5.22): Saved Searches / Smart Lists — reusable filters for list views

- SavedFilter model with TenantMixin (name, entity_type, filter_criteria JSONB, user_id)
- Routes: GET/POST /saved-filters, DELETE /saved-filters/{id} with RBAC
- Alembic migration 0029_saved_filters creates saved_filters table
- Frontend: SavedFilters.tsx component with save/load/delete UI
- Frontend: api/savedFilters.ts with React Query hooks
- Integrated into ContactsListPage as example
- i18n keys for savedFilters.* in de.json and en.json
- Tests: test_saved_filters.py (9 tests) + SavedFilters.test.tsx (3 tests)
- Registered SavedFilter in conftest.py

app/models/saved_filter.py

@@ -0,0 +1,36 @@
+"""SavedFilter model — tenant-scoped, user-scoped saved filter criteria."""
+
+from __future__ import annotations
+
+import uuid
+from typing import Any
+
+from sqlalchemy import ForeignKey, Index, String, UniqueConstraint
+from sqlalchemy.dialects.postgresql import JSONB
+from sqlalchemy.dialects.postgresql import UUID as PGUUID
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.core.db import Base, TenantMixin
+
+
+class SavedFilter(Base, TenantMixin):
+    """Saved filter — reusable filter criteria for list views (contacts, mail, calendar, DMS)."""
+
+    __tablename__ = "saved_filters"
+    __table_args__ = (
+        UniqueConstraint("tenant_id", "user_id", "entity_type", "name", name="uq_saved_filters_tenant_user_entity_name"),
+        Index("ix_saved_filters_tenant_user", "tenant_id", "user_id"),
+        Index("ix_saved_filters_tenant_entity", "tenant_id", "entity_type"),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    name: Mapped[str] = mapped_column(String(100), nullable=False)
+    entity_type: Mapped[str] = mapped_column(
+        String(50), nullable=False
+    )  # contacts, mail, calendar, dms
+    filter_criteria: Mapped[dict[str, Any]] = mapped_column(JSONB, nullable=False, default=dict)
+    user_id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True), ForeignKey("users.id", ondelete="CASCADE"), nullable=False
+    )