fix: analyst ratings timeout + add accession column to institution_filings

- Add 6s server-side timeout to Yahoo Finance quoteSummary (Promise.race) so the backend responds with stale data instead of hanging indefinitely. Stale cache is served on error (router.ts:1895-1898), matching ADR-0009.
- Hoist YahooFinance to a module-level singleton (getYf()) so the crumb/cookie is fetched once, not per call. Matches YFinanceAdapter pattern.
- Add suppressNotices for yahooSurvey to reduce log noise.
- Add accession column to institution_filings (schema.sql + migration in client.ts) and thread it through both secDataFetcher.ts INSERT paths (13D/G and 13F-HR). Fixes recurring `no such column: accession` error in new13daProducer alert tick.
- new13daProducer.ts needs no changes - its SELECT accession query now works.

app/server/src/db/schema.sql

@@ -113,7 +113,8 @@ CREATE TABLE IF NOT EXISTS institution_filings (
   shares           REAL,                  -- shares reported
   value_usd        REAL,
   reported_quarter TEXT NOT NULL,         -- calendar quarter positions are "as of"
-  filed_at         TEXT NOT NULL,
+  filed_at         TEXT NOT NULL,         -- when the filing was submitted to SEC
+  accession        TEXT,                  -- SEC accession number (enables 13D/G dedup)
   fetched_at       TEXT NOT NULL,
   put_call         TEXT                   -- Put|Call|null for common stock (13F only)
 );