fix: backfill symbol_demand for sidebar-added symbols + analyst ratings schema fix

- Add await ctx.cache.subscribe() to addSymbol mutation so symbols
  added via the sidebar get registered in symbol_demand and yfinance
  jobs are queued immediately
- Backfill PEP, WYNN, STZ, CELH into symbol_demand + adapter_queue
- Upgrade yahoo-finance2 3.15.3 -> 3.15.4 and pass validateResult:false
  to quoteSummary() to handle Yahoo schema drift
- Add error detail logging for analyst ratings schema failures
- Update .gitignore with common ignores

app/server/src/x/backfill.ts

@@ -0,0 +1,37 @@
+// Investor Flow — X backfill (Slice 16 follow-up).
+// On first-add of a tracked account, walk the account's timeline AND the symbol's
+// cashtag back N days (default 30) and persist every post into x_cookie_posts.
+// Rate-limited by XCookieAdapter's own 1 req / 3s TokenBucket, so this is a
+// background job — callers fire-and-forget (do not await in the request path).
+import type { DatabaseSync } from 'node:sqlite';
+import { XCookieAdapter } from '../adapters/XCookieAdapter.ts';
+
+const DEFAULT_BACKFILL_DAYS = 30;
+
+export async function backfillAccount(
+  db: DatabaseSync,
+  symbol: string,
+  handle: string,
+  days: number = DEFAULT_BACKFILL_DAYS,
+): Promise<void> {
+  const row = db.prepare('SELECT ct0_enc, auth_token_enc FROM x_credentials WHERE id=?').get('singleton') as
+    { ct0_enc?: string | null; auth_token_enc?: string | null } | undefined;
+  if (!row || !row.ct0_enc || !row.auth_token_enc) {
+    console.warn('[x-backfill] skipped — no X credentials configured');
+    return;
+  }
+
+  const cryptoMod: any = await import('../lib/crypto.ts');
+  const creds = {
+    ct0: cryptoMod.default.decrypt(row.ct0_enc),
+    auth_token: cryptoMod.default.decrypt(row.auth_token_enc),
+  };
+  const adapter = new XCookieAdapter(creds, undefined, db);
+
+  try {
+    await adapter.trustedTimeline(handle, { walkBackDays: days });
+    console.log(`[x-backfill] timeline ${handle} (${days}d) done`);
+  } catch (e) {
+    console.error(`[x-backfill] timeline ${handle} failed:`, e instanceof Error ? e.message : e);
+  }
+}