fix: trend_windows now upserts instead of accumulating (7.5GB→4MB), add competitive signal retention cleanup

infra/migrations/023_trend_windows_upsert_and_cleanup.sql

@@ -0,0 +1,23 @@
+-- Fix trend_windows to upsert instead of accumulating rows.
+-- Add unique constraint so ON CONFLICT works, then deduplicate existing data.
+
+-- Step 1: Keep only the most recent row per (entity_type, entity_id, window)
+DELETE FROM trend_windows
+WHERE id NOT IN (
+    SELECT DISTINCT ON (entity_type, entity_id, "window") id
+    FROM trend_windows
+    ORDER BY entity_type, entity_id, "window", generated_at DESC
+);
+
+-- Step 2: Add unique constraint for upsert
+CREATE UNIQUE INDEX IF NOT EXISTS idx_trend_windows_entity_window
+    ON trend_windows (entity_type, entity_id, "window");
+
+-- Step 3: Clean up old competitive signal records (keep last 30 days)
+DELETE FROM competitive_signal_records
+WHERE computed_at < NOW() - INTERVAL '30 days';
+
+-- Step 4: Add a partial index to speed up the NOT EXISTS check in the
+-- aggregation propagation query
+CREATE INDEX IF NOT EXISTS idx_competitive_signals_source_doc_ticker
+    ON competitive_signal_records (source_document_id, source_ticker);