feat: add Polygon grouped daily endpoint for broad market data

Two tiers of market data:
1. Per-ticker prev bars (existing 50 sources, 15-min cadence) for
   watchlist detail — trading decisions, stop-loss, position sizing
2. Grouped daily (new single source, once per day) for broad market
   context — correlation analysis, sector rotation, competitive intel

Changes:
- Add grouped_daily endpoint to PolygonMarketAdapter with auto date
  calculation (previous trading day, skip weekends)
- Add fetch_global_market_sources() to scheduler for sources without
  company_id, scheduled once daily (86400s cadence)
- Update _persist_market_items to use item-level ticker from T field
  and look up company_id dynamically for grouped daily bars
- Migration 020: make company_id nullable on sources and
  market_snapshots tables, add grouped daily source row
- Fix backtest replay to query market_snapshots data->>'c' for prices

services/scheduler/app.py

@@ -225,6 +225,28 @@ async def fetch_macro_sources(pool: asyncpg.Pool) -> list[asyncpg.Record]:
     )
 
 
+async def fetch_global_market_sources(pool: asyncpg.Pool) -> list[asyncpg.Record]:
+    """Fetch active market sources that are not company-specific.
+
+    These are sources like the grouped daily endpoint that fetch data for
+    all tickers in a single API call. They have company_id IS NULL and
+    source_type = 'market_api'.
+    """
+    return await pool.fetch(
+        """SELECT s.id AS source_id,
+                  s.company_id,
+                  s.source_type,
+                  s.source_name,
+                  s.config,
+                  s.credibility_score
+           FROM sources s
+           WHERE s.active = TRUE
+             AND s.source_type = 'market_api'
+             AND s.company_id IS NULL
+           ORDER BY s.source_name"""
+    )
+
+
 async def fetch_aliases_for_company(pool: asyncpg.Pool, company_id: str) -> list[str]:
     """Fetch all aliases for a company."""
     rows = await pool.fetch(
@@ -360,9 +382,58 @@ async def schedule_cycle(pool: asyncpg.Pool, rds: aioredis.Redis) -> int:
             "Enqueued macro_news job for %s", src["source_name"],
         )
 
+    # --- Schedule global market sources (grouped daily, etc.) ---
+    global_market_sources = await fetch_global_market_sources(pool)
+    for src in global_market_sources:
+        source_id = src["source_id"]
+        source_type = src["source_type"]
+        source_config = _ensure_dict(src["config"])
+
+        # Use a longer cadence for grouped daily (once per day = 86400s)
+        endpoint = source_config.get("endpoint", "")
+        if endpoint == "grouped_daily":
+            source_config.setdefault("polling_interval_seconds", 86400)
+
+        last_run = await fetch_last_run(pool, source_id)
+
+        last_completed_at = None
+        last_status = None
+        retry_count = 0
+        next_retry_at = None
+
+        if last_run:
+            last_status = last_run["status"]
+            last_completed_at = last_run["completed_at"] or last_run["started_at"]
+            retry_count = last_run["retry_count"] or 0
+            next_retry_at = last_run["next_retry_at"]
+
+        if not is_source_due(
+            source_type=source_type,
+            source_config=source_config,
+            last_completed_at=last_completed_at,
+            last_status=last_status,
+            retry_count=retry_count,
+            next_retry_at=next_retry_at,
+            now=now,
+        ):
+            skipped_not_due += 1
+            continue
+
+        if not await check_rate_limit(rds, source_type, now):
+            skipped_rate_limit += 1
+            continue
+
+        # Build job with ticker="_MARKET" for global sources
+        job = build_job_payload(src, [], now)
+        job["ticker"] = "_MARKET"
+        await rds.rpush(queue_key(QUEUE_INGESTION), json.dumps(job))
+        enqueued += 1
+
+        logger.info("Enqueued grouped daily market data job")
+
     logger.info(
         "Cycle complete: enqueued=%d skipped_not_due=%d skipped_rate_limit=%d total_sources=%d",
-        enqueued, skipped_not_due, skipped_rate_limit, len(sources) + len(macro_sources),
+        enqueued, skipped_not_due, skipped_rate_limit, len(sources) + len(macro_sources) + len(global_market_sources),
     )
     return enqueued