fix: select shadow book setups by scan run id, not a time window

The run-id marker proved which scan wrote last, but the shadow book still
selected setups by detected_at >= scan_start. An overlapping manual scan
could insert rows in that same window; if the pipeline's scan wrote the
marker last its id matched and the shadow book proceeded, then swept in --
or ranked highest -- a manual-scan row. The identity check gated entry but
selection did not.

Carry the run id onto the rows. Migration 025 adds an indexed
trade_setups.scan_run_id. scan_all_tickers computes one id per run
(pipeline's when a step, else fresh), passes it to scan_ticker which stamps
every row after enhancement, and writes the same id to the completion
marker. The shadow book selects WHERE scan_run_id == the matched id, so a
concurrent scan's rows are excluded by identity regardless of their
detected_at. The now-unused STARTED marker is dropped; COMPLETED
(freshness) and RUN_ID (identity) remain.

Decisive test: the pipeline's id matches, but a same-window manual row with
a higher rank is present and is excluded -- only the pipeline's own row is
traded. A time-window select would have swept it in and ranked it first.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

alembic/versions/025_trade_setup_scan_run_id.py

@@ -0,0 +1,38 @@
+"""trade_setup scan_run_id — identity of the producing scan run
+
+Revision ID: 025
+Revises: 024
+Create Date: 2026-07-21 00:00:00.000000
+
+The shadow book must select the exact batch produced by its pipeline's scan.
+Matching the scan-completion marker's run id proves which scan wrote last, but
+setup selection was still a detected_at window that a concurrent manual scan
+could write rows into. Stamping each row with its scan's run id lets the shadow
+book select by identity instead. Existing rows are null (they predate the
+column and are never traded by the shadow book).
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision: str = "025"
+down_revision: Union[str, None] = "024"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column(
+        "trade_setups",
+        sa.Column("scan_run_id", sa.String(length=32), nullable=True),
+    )
+    op.create_index(
+        "ix_trade_setups_scan_run_id", "trade_setups", ["scan_run_id"]
+    )
+
+
+def downgrade() -> None:
+    op.drop_index("ix_trade_setups_scan_run_id", table_name="trade_setups")
+    op.drop_column("trade_setups", "scan_run_id")