feat: wire Tufts SCO to DentaQuest portal and fix insurance credential dropdown

- Add /dentaquest-eligibility endpoint in Python agent (Tufts SCO uses providers.dentaquest.com)
- Add backend route, processor, and service client for Tufts SCO (separate from UnitedSCO/DentalHub)
- Fix Tufts SCO button to post to new tuftssco route instead of unitedsco
- Fix credential field names: dentaquestUsername/Password (was tuftsscoUsername/Password)
- Fix socket event: listen for selenium:dentaquest_session_started (was unitedsco)
- Fix error visibility: keep session alive 30s on error so backend reads real message
- Replace free-text Site Key field with dropdown to prevent key mismatches

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/Frontend/src/components/settings/InsuranceCredForm.tsx

@@ -15,6 +15,15 @@ type CredentialFormProps = {
   };
 };
 
+const SITE_KEY_OPTIONS = [
+  { value: "MH", label: "MassHealth (MH)" },
+  { value: "DDMA", label: "Delta Dental MA (DDMA)" },
+  { value: "DELTAINS", label: "Delta Dental Ins (DELTAINS)" },
+  { value: "TUFTS_SCO", label: "Tufts SCO (TUFTS_SCO)" },
+  { value: "UNITED_SCO", label: "United SCO (UNITED_SCO)" },
+  { value: "CCA", label: "CCA (CCA)" },
+];
+
 export function CredentialForm({ onClose, userId, defaultValues }: CredentialFormProps) {
   const [siteKey, setSiteKey] = useState(defaultValues?.siteKey || "");
   const [username, setUsername] = useState(defaultValues?.username || "");
@@ -93,14 +102,19 @@ export function CredentialForm({ onClose, userId, defaultValues }: CredentialFor
         </h2>
         <form onSubmit={handleSubmit} className="space-y-4">
           <div>
-            <label className="block text-sm font-medium">Site Key</label>
-            <input
-              type="text"
+            <label className="block text-sm font-medium">Insurance</label>
+            <select
               value={siteKey}
               onChange={(e) => setSiteKey(e.target.value)}
-              className="mt-1 p-2 border rounded w-full"
-              placeholder="e.g., MH, Delta MA, (keep the site key exact same)"
-            />
+              className="mt-1 p-2 border rounded w-full bg-white"
+            >
+              <option value="">— Select insurance —</option>
+              {SITE_KEY_OPTIONS.map((opt) => (
+                <option key={opt.value} value={opt.value}>
+                  {opt.label}
+                </option>
+              ))}
+            </select>
           </div>
           <div>
             <label className="block text-sm font-medium">Username</label>