feat: admin-configurable FINRA download URL

- Add finra_config singleton table (base_url + updated_at)
- Add getFinraBaseUrl() and setFinraBaseUrl() to admin.ts
  Resolution order: DB config > env FINRA_BASE_URL > built-in default
- Add finraConfig query + finraConfigUpdate mutation to admin tRPC router
- Update FinraIngestService.downloadAndIngestFinra to accept optional baseUrl
  param; falls back to getFinraBaseUrl(db) when omitted
- FinraBulkAdapter resolves URL implicitly via the service (no adapter change)
- Add migration #10 for existing DBs

app/server/src/db/client.ts

@@ -232,6 +232,17 @@ function runMigrations(db: DatabaseSync): void {
       )
     `);
   } catch { /* ignore */ }
+
+  // 10. FINRA config table for admin-configurable download URL.
+  try {
+    db.exec(`
+      CREATE TABLE IF NOT EXISTS finra_config (
+        id          TEXT PRIMARY KEY DEFAULT 'singleton',
+        base_url    TEXT NOT NULL DEFAULT 'https://www.finra.org/sites/default/files',
+        updated_at  TEXT NOT NULL
+      )
+    `);
+  } catch { /* ignore */ }
 }
 
 let _db: DatabaseSync | null = null;