fix(send-email-link): use plural connections with condition filter

The GetUser and GetDatabaseInfo queries used singular root fields
`user(id:)` and `database(id:)`. These are not exposed by the
constructive server: ConstructivePreset extends NoUniqueLookupPreset
(see constructive/graphile/graphile-settings/src/plugins/primary-key-only.ts),
which deliberately disables singular root-field lookups by unique
constraint — including primary key — to keep the API surface small.

Calling these queries against a real constructive server returns:

  Cannot query field "database" on type "Query".
  Did you mean "databases" or "tables"?

Switch to the plural-connection-with-condition form, matching the
older in-monorepo implementation (see
constructive/functions/send-email-link/src/index.ts on the constructive
repo). Update the destructure paths to walk through .nodes[0]
accordingly.

This wasn't caught by the existing tests because
functions/send-email-link/__tests__/handler.graphql.test.ts contains
only it.todo placeholders, and the validation tests in handler.test.ts
mock the meta/client clients with jest.fn().mockResolvedValue(). The
queries had never actually been run against a real constructive server.

Surfaced by constructive-hub PR #137, which is the first integration
running this fn-runtime against a fully-deployed constructive stack.

Author: Anmol1696

functions/send-email-link/handler.ts

@@ -6,37 +6,47 @@ import { send as sendPostmaster } from '@constructive-io/postmaster';
 import { send as sendSmtp } from 'simple-smtp-server';
 import { parseEnvBoolean } from '@pgpmjs/env';
 
+// Use plural connections with `condition` filter rather than singular-by-PK
+// (`user(id:)`, `database(id:)`). The constructive server's preset extends
+// NoUniqueLookupPreset, which deliberately disables singular root-field
+// lookups by unique constraint (including primary key) to keep the API
+// surface small. The plural+condition form is the supported way to fetch
+// a row by id.
 const GetUser = gql`
   query GetUser($userId: UUID!) {
-    user(id: $userId) {
-      username
-      displayName
-      profilePicture
+    users(condition: { id: $userId }, first: 1) {
+      nodes {
+        username
+        displayName
+        profilePicture
+      }
     }
   }
 `;
 
 const GetDatabaseInfo = gql`
   query GetDatabaseInfo($databaseId: UUID!) {
-    database(id: $databaseId) {
-      sites {
-        nodes {
-          domains {
-            nodes {
-              subdomain
-              domain
+    databases(condition: { id: $databaseId }, first: 1) {
+      nodes {
+        sites {
+          nodes {
+            domains {
+              nodes {
+                subdomain
+                domain
+              }
             }
-          }
-          logo
-          title
-          siteThemes {
-            nodes {
-              theme
+            logo
+            title
+            siteThemes {
+              nodes {
+                theme
+              }
             }
-          }
-          siteModules(condition: { name: "legal_terms_module" }) {
-            nodes {
-              data
+            siteModules(condition: { name: "legal_terms_module" }) {
+              nodes {
+                data
+              }
             }
           }
         }
@@ -111,7 +121,7 @@ const sendEmailLink = async (
     databaseId
   });
 
-  const site = databaseInfo?.database?.sites?.nodes?.[0];
+  const site = databaseInfo?.databases?.nodes?.[0]?.sites?.nodes?.[0];
   if (!site) {
     throw new Error('Site not found for database');
   }
@@ -177,7 +187,7 @@ const sendEmailLink = async (
       const inviter = await client.request<any>(GetUser, {
         userId: params.sender_id
       });
-      inviterName = inviter?.user?.displayName;
+      inviterName = inviter?.users?.nodes?.[0]?.displayName;
 
       if (inviterName) {
         subject = `${inviterName} invited you to ${nick}!`;