feat(db): bulk add_logs for one-commit ingestion batches

Adds BaseRepository.add_logs (default: loops add_log for backwards
compatibility) and a real single-session/single-commit implementation
on SQLModelRepository. Introduces DECNET_BATCH_SIZE (default 100) and
DECNET_BATCH_MAX_WAIT_MS (default 250) so the ingester can flush on
either a size or a time bound when it adopts the new method.

Ingester wiring is deferred to a later pass — the single-log path was
deadlocking tests when flushed during lifespan teardown, so this change
ships the DB primitive alone.

decnet/web/db/repository.py

@@ -15,6 +15,15 @@ class BaseRepository(ABC):
         """Add a new log entry to the database."""
         pass
 
+    async def add_logs(self, log_entries: list[dict[str, Any]]) -> None:
+        """Bulk-insert log entries in a single transaction.
+
+        Default implementation falls back to per-row add_log; concrete
+        repositories should override for a real single-commit insert.
+        """
+        for _entry in log_entries:
+            await self.add_log(_entry)
+
     @abstractmethod
     async def get_logs(
         self,

decnet/web/db/sqlmodel_repo.py

@@ -145,7 +145,8 @@ class SQLModelRepository(BaseRepository):
 
     # ---------------------------------------------------------------- logs
 
-    async def add_log(self, log_data: dict[str, Any]) -> None:
+    @staticmethod
+    def _normalize_log_row(log_data: dict[str, Any]) -> dict[str, Any]:
         data = log_data.copy()
         if "fields" in data and isinstance(data["fields"], dict):
             data["fields"] = orjson.dumps(data["fields"]).decode()
@@ -156,11 +157,23 @@ class SQLModelRepository(BaseRepository):
                 )
             except ValueError:
                 pass
+        return data
 
+    async def add_log(self, log_data: dict[str, Any]) -> None:
+        data = self._normalize_log_row(log_data)
         async with self._session() as session:
             session.add(Log(**data))
             await session.commit()
 
+    async def add_logs(self, log_entries: list[dict[str, Any]]) -> None:
+        """Bulk insert — one session, one commit for the whole batch."""
+        if not log_entries:
+            return
+        _rows = [Log(**self._normalize_log_row(e)) for e in log_entries]
+        async with self._session() as session:
+            session.add_all(_rows)
+            await session.commit()
+
     def _apply_filters(
         self,
         statement: SelectOfScalar,