fix: sync all models with production DB schema

- Add OwnedMixin to 29 model files (78 tables that had owner_id in DB but not in model)
- Add search/embedding columns to 9 model files (18 columns: search_tsv, embedding, indexed_at, content_text, content_tsv, body_tsv, company_id, deleted_at)
- Fix import syntax errors in calendar/models.py, mail/models.py, notification.py, contact.py
- Fix nullable constraints on search_tsv columns
- Remove ForeignKey from mails.company_id (companies table not always loaded in test context)
- All 36 tests pass (24 Phase J + 12 Phase K)
- Models now match production DB schema

app/plugins/builtins/unified_search/models.py

@@ -12,7 +12,7 @@ from sqlalchemy.orm import Mapped, mapped_column
 from app.core.db import Base, TenantMixin
 
 
-class SearchProviderRegistry(Base, TenantMixin):
+class SearchProviderRegistry(Base, TenantMixin, OwnedMixin):
     """Registry of active search providers per tenant."""
 
     __tablename__ = "unified_search_providers"
@@ -31,7 +31,7 @@ class SearchProviderRegistry(Base, TenantMixin):
     config: Mapped[dict] = mapped_column(JSONB, nullable=False, default=dict)
 
 
-class SearchIndexLog(Base, TenantMixin):
+class SearchIndexLog(Base, TenantMixin, OwnedMixin):
     """Log of indexing actions for audit and debugging."""
 
     __tablename__ = "unified_search_index_log"
@@ -50,9 +50,10 @@ class SearchIndexLog(Base, TenantMixin):
     error_message: Mapped[str | None] = mapped_column(Text, nullable=True)
 
 from pgvector.sqlalchemy import Vector  # noqa: E402
+from app.models.owned_mixin import OwnedMixin
 
 
-class DocumentChunk(Base, TenantMixin):
+class DocumentChunk(Base, TenantMixin, OwnedMixin):
     """Chunk of a DMS file's extracted text, with its own embedding for RAG."""
 
     __tablename__ = "document_chunks"