add earnings-date guard — warn when a report falls in the target horizon

Finnhub's earnings calendar now supplies next_earnings_date through the
fundamentals chain; persisted on fundamental_data (migration 006) and exposed in
the fundamentals API. The recommendation panel warns when earnings fall within
the ~30-day target horizon (a report can gap price through stop/target) and
otherwise shows the next date. Informational only.

Deploy: run alembic upgrade (new fundamental_data.next_earnings_date column).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

alembic/versions/006_add_next_earnings_date.py

@@ -0,0 +1,29 @@
+"""add next_earnings_date to fundamental_data
+
+Revision ID: 006
+Revises: 005
+Create Date: 2026-06-15 00:00:00.000000
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = "006"
+down_revision: Union[str, None] = "005"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column(
+        "fundamental_data",
+        sa.Column("next_earnings_date", sa.Date(), nullable=True),
+    )
+
+
+def downgrade() -> None:
+    op.drop_column("fundamental_data", "next_earnings_date")