fix(postgres): default absent sslmode to prefer

apps/desktop/src/components/connection/ConnectionDialog.vue

@@ -5621,7 +5621,7 @@ function openExternalUrl(url: string) {
                                     ? 'catalog=paimon_catalog'
                                     : form.db_type === 'cassandra'
                                       ? 'localdatacenter=dc1'
-                                      : 'sslmode=disable'
+                                      : 'sslmode=prefer'
                       "
                     />
                   </div>

apps/desktop/src/lib/connection/__tests__/postgresTlsMode.spec.ts

@@ -2,8 +2,8 @@ import { describe, expect, it } from "vitest";
 import { postgresTlsModeForForm } from "@/lib/connection/postgresTlsMode";
 
 describe("postgresTlsModeForForm", () => {
-  it("uses disable when legacy connections have no explicit mode", () => {
-    expect(postgresTlsModeForForm(undefined, false)).toBe("disable");
+  it("uses prefer when legacy connections have no explicit mode", () => {
+    expect(postgresTlsModeForForm(undefined, false)).toBe("prefer");
   });
 
   it("keeps the legacy TLS toggle mapped to require", () => {
@@ -12,6 +12,7 @@ describe("postgresTlsModeForForm", () => {
 
   it("honors explicit modes and aliases", () => {
     expect(postgresTlsModeForForm("disable", false)).toBe("disable");
+    expect(postgresTlsModeForForm("prefer", false)).toBe("prefer");
     expect(postgresTlsModeForForm("verify_identity", false)).toBe("verify-full");
   });
 });

apps/desktop/src/lib/connection/postgresTlsMode.ts

@@ -12,7 +12,8 @@ export function postgresTlsModeForForm(value: string | undefined, ssl: boolean |
     case "verify-identity":
       return "verify-full";
     default:
-      // DBX and DBeaver expose TLS as opt-in; an absent mode must remain plaintext.
-      return ssl ? "require" : "disable";
+      // Align with libpq/JDBC: absent mode prefers TLS and can fall back to plaintext.
+      // Legacy ssl=true still maps to require.
+      return ssl ? "require" : "prefer";
   }
 }