feat(dolt): add shares_outstanding_date to fundamental_snapshots (026)

A1 carry-forward. The SEC cover-page share count
(dei:EntityCommonStockSharesOutstanding) is reported "as of" its own date, which
can differ from the fiscal period_end — store that date so market cap uses the
right point-in-time count. Migration 026 edited in place (never run with data).

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

alembic/versions/026_dolt_fundamentals_schema.py

@@ -66,6 +66,7 @@ def upgrade() -> None:
         sa.Column("cash_and_st_investments", sa.Float(), nullable=True),
         sa.Column("total_debt", sa.Float(), nullable=True),
         sa.Column("shares_outstanding", sa.Float(), nullable=True),
+        sa.Column("shares_outstanding_date", sa.Date(), nullable=True),
         sa.Column(
             "import_run_id",
             sa.Integer(),

app/models/fundamental_snapshot.py

@@ -64,6 +64,10 @@ class FundamentalSnapshot(Base):
     cash_and_st_investments: Mapped[float | None] = mapped_column(Float, nullable=True)
     total_debt: Mapped[float | None] = mapped_column(Float, nullable=True)
     shares_outstanding: Mapped[float | None] = mapped_column(Float, nullable=True)
+    # The cover-page share count (dei:EntityCommonStockSharesOutstanding) is
+    # reported "as of" its own date, which can differ from period_end — store it
+    # so market cap uses the right point-in-time count.
+    shares_outstanding_date: Mapped[date | None] = mapped_column(Date, nullable=True)
 
     import_run_id: Mapped[int | None] = mapped_column(
         ForeignKey("data_import_runs.id", ondelete="SET NULL"), nullable=True