fix(types): P2 — wire _MixinBase + col() across sqlmodel_repo; suppress pydantic/SQLModel column typing false positives

- Add _MixinBase abstract class to _helpers.py: declares _session(),
  _deserialize_attacker(), _assert_pending(), _check_and_bump_version(),
  and list_running_topology_deckies() so mypy can see cross-mixin contracts
- Add _require(val, msg) helper for narrowing T | None → T
- Inherit _MixinBase in all 26 leaf mixin classes
- Wrap SQLAlchemy column method calls (.is_(), .like(), .notin_(), .in_(),
  .contains()) with col() from sqlmodel — fixes attr-defined false positives
  caused by pydantic plugin typing class-level fields as Python value types
- Wrap select(Model.field) with select(col(Model.field)) for column projections
- Add pyproject.toml [[tool.mypy.overrides]] to disable arg-type in
  sqlmodel_repo.*: pydantic plugin resolves .where(Model.field == v) as
  where(bool), a false positive; call-arg still catches real argument errors
- Remove 9 stale # type: ignore comments (logging, helpers, credentials)
- Fix telemetry.py traced() overload no-redef + misc
- Fix logs.py datetime/str operator and nullable PK comparison with col()
- sqlmodel_repo/ now has 0 mypy errors

decnet/web/db/sqlmodel_repo/campaigns.py

@@ -11,11 +11,14 @@ from datetime import datetime, timezone
 from typing import Any, Optional
 
 from sqlalchemy import desc, func, select, update
+from sqlmodel import col
 
 from decnet.web.db.models import AttackerIdentity, Campaign
 
 
-class CampaignsMixin:
+from decnet.web.db.sqlmodel_repo._helpers import _MixinBase
+
+class CampaignsMixin(_MixinBase):
     """Mixin: composed onto ``SQLModelRepository``."""
 
     async def get_campaign_by_uuid(self, uuid: str) -> Optional[dict[str, Any]]:
@@ -41,7 +44,7 @@ class CampaignsMixin:
     ) -> list[dict[str, Any]]:
         statement = (
             select(Campaign)
-            .where(Campaign.merged_into_uuid.is_(None))
+            .where(col(Campaign.merged_into_uuid).is_(None))
             .order_by(desc(Campaign.updated_at))
             .offset(offset)
             .limit(limit)
@@ -54,7 +57,7 @@ class CampaignsMixin:
         statement = (
             select(func.count())
             .select_from(Campaign)
-            .where(Campaign.merged_into_uuid.is_(None))
+            .where(col(Campaign.merged_into_uuid).is_(None))
         )
         async with self._session() as session:
             result = await session.execute(statement)
@@ -91,7 +94,7 @@ class CampaignsMixin:
         # graph reads. Narrow on purpose — future denormalised
         # projections (commands_by_phase from log mining, decky-set
         # aggregates) can land here without churning callers.
-        statement = select(
+        statement = select(  # type: ignore[call-overload, misc]
             AttackerIdentity.uuid,
             AttackerIdentity.campaign_id,
             AttackerIdentity.merged_into_uuid,