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/kommunikation/models.py

@@ -54,7 +54,7 @@ class CommConversation(Base, TenantMixin, OwnedMixin):
     metadata_: Mapped[dict[str, Any]] = mapped_column("metadata", JSONB, default=dict, nullable=False)
 
 
-class CommParticipant(Base, TenantMixin):
+class CommParticipant(Base, TenantMixin, OwnedMixin):
     """Participant in a conversation — user, ai, system, gateway, etc."""
 
     __tablename__ = "comm_participants"
@@ -84,7 +84,7 @@ class CommParticipant(Base, TenantMixin):
     left_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
 
 
-class CommMessage(Base, TenantMixin):
+class CommMessage(Base, TenantMixin, OwnedMixin):
     """Message in a conversation — text content plus rich content blocks."""
 
     __tablename__ = "comm_messages"
@@ -117,7 +117,7 @@ class CommMessage(Base, TenantMixin):
     edited_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
 
 
-class CommMessageBlock(Base, TenantMixin):
+class CommMessageBlock(Base, TenantMixin, OwnedMixin):
     """Rich content block attached to a message."""
 
     __tablename__ = "comm_message_blocks"
@@ -139,7 +139,7 @@ class CommMessageBlock(Base, TenantMixin):
     sort_order: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
 
 
-class CommMessageAttachment(Base, TenantMixin):
+class CommMessageAttachment(Base, TenantMixin, OwnedMixin):
     """File attachment on a message — DMS reference or comm-internal upload."""
 
     __tablename__ = "comm_message_attachments"
@@ -165,7 +165,7 @@ class CommMessageAttachment(Base, TenantMixin):
     metadata_: Mapped[dict[str, Any]] = mapped_column("metadata", JSONB, default=dict, nullable=False)
 
 
-class CommMessageReaction(Base, TenantMixin):
+class CommMessageReaction(Base, TenantMixin, OwnedMixin):
     """Emoji reaction on a message."""
 
     __tablename__ = "comm_message_reactions"
@@ -187,7 +187,7 @@ class CommMessageReaction(Base, TenantMixin):
     emoji: Mapped[str] = mapped_column(String(50), nullable=False)
 
 
-class CommMessageRead(Base, TenantMixin):
+class CommMessageRead(Base, TenantMixin, OwnedMixin):
     """Read state per user per conversation."""
 
     __tablename__ = "comm_message_reads"
@@ -215,7 +215,7 @@ class CommMessageRead(Base, TenantMixin):
     )
 
 
-class CommConversationPin(Base, TenantMixin):
+class CommConversationPin(Base, TenantMixin, OwnedMixin):
     """User-specific conversation pinning."""
 
     __tablename__ = "comm_conversation_pins"
@@ -238,7 +238,7 @@ class CommConversationPin(Base, TenantMixin):
     )
 
 
-class CommConversationMute(Base, TenantMixin):
+class CommConversationMute(Base, TenantMixin, OwnedMixin):
     """User-specific conversation muting."""
 
     __tablename__ = "comm_conversation_mutes"
@@ -261,7 +261,7 @@ class CommConversationMute(Base, TenantMixin):
     )
 
 
-class CommMessageEdit(Base, TenantMixin):
+class CommMessageEdit(Base, TenantMixin, OwnedMixin):
     """Edit history for messages — stores old content before each edit."""
 
     __tablename__ = "comm_message_edits"