cleanup: drop redundant @pytest.mark.asyncio + fix log_id type

- pyproject already sets asyncio_mode=auto, so async def tests are
  collected as async automatically. Removed the redundant decorator
  from four files (test_i18n, test_llm_csv_parser, test_ticker_validate,
  test_localization_integration); the bare async def is enough.
- StrategicLogTranslation.log_id used the _PK autoincrement type for
  a non-PK FK column. Replaced with a portable BigInteger that emits
  Integer on SQLite and BigInteger elsewhere — matches the migration's
  sa.BigInteger() declaration.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/models.py

@@ -136,7 +136,9 @@ class StrategicLogTranslation(Base):
 
     id: Mapped[int] = mapped_column(_PK, primary_key=True, autoincrement=True)
     log_id: Mapped[int] = mapped_column(
-        _PK, ForeignKey("strategic_logs.id", ondelete="CASCADE"), nullable=False,
+        BigInteger().with_variant(Integer(), "sqlite"),
+        ForeignKey("strategic_logs.id", ondelete="CASCADE"),
+        nullable=False,
     )
     lang: Mapped[str] = mapped_column(String(8), nullable=False)
     content_md: Mapped[str] = mapped_column(Text, nullable=False)