models: add User.lang + StrategicLogTranslation

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

app/models.py

@@ -120,6 +120,37 @@ class StrategicLog(Base):
     cost_usd: Mapped[float | None] = mapped_column(Float)
 
 
+class StrategicLogTranslation(Base):
+    """Cached translation of a single StrategicLog row.
+
+    Populated by ai_log_job after the English row is committed: one
+    row per (log_id, lang) combination. The /log endpoint serves the
+    matching row when available and falls back to the English source
+    when no row exists yet (e.g. translation failed or the language
+    was added after the log was generated).
+
+    No user attribution — the cache is shared. Setting `lang` on a
+    user just selects which (already-translated) variant they see.
+    """
+    __tablename__ = "strategic_log_translations"
+
+    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,
+    )
+    lang: Mapped[str] = mapped_column(String(8), nullable=False)
+    content_md: Mapped[str] = mapped_column(Text, nullable=False)
+    generated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, default=utcnow,
+    )
+    llm_model: Mapped[str | None] = mapped_column(String(64))
+    llm_cost_usd: Mapped[float | None] = mapped_column(Float)
+
+    __table_args__ = (
+        UniqueConstraint("log_id", "lang", name="uq_slt_log_lang"),
+    )
+
+
 class IndicatorSummary(Base):
     """Short AI-generated read for one indicator group, regenerated hourly.
     The latest row per group_name is what the dashboard renders."""
@@ -189,6 +220,13 @@ class User(Base):
     # NULL = use INTERMEDIATE at render time. Server-side mirror of the
     # dashboard tone, decoupled because the dashboard pref is localStorage.
     digest_tone: Mapped[str | None] = mapped_column(String(16))
+    # Preferred language for AI-generated content (strategic log,
+    # digest emails, portfolio commentary). Default 'en'. The settings
+    # PATCH endpoint validates against ACTIVE_LANGUAGES in
+    # app/services/i18n.py before writing.
+    lang: Mapped[str] = mapped_column(
+        String(8), nullable=False, default="en", server_default="en",
+    )
     # Polar (MoR) linkage — populated by the polar_webhook handler the
     # first time we see a subscription/order event for the user. The
     # customer id is the stable join key; the subscription id is what