fix(send-email-link): use 'where' filter instead of 'condition'

The previous fix (#38) switched from singular-by-PK lookups to plural
connections with the built-in postgraphile `condition:` argument.
That works on a stock postgraphile server, but not on constructive:
ConstructivePreset (constructive/graphile/graphile-settings/src/presets/constructive-preset.ts)
explicitly disables PgConditionArgumentPlugin and PgConditionCustomFieldsPlugin,
replacing `condition:` with the more powerful `where:` filter
provided by graphile-connection-filter.

Calling the queries against a real constructive server returns:

  Unknown argument "condition" on field "Query.databases".
  Unknown argument "condition" on field "Site.siteModules".
  status: 400

Switch all `condition:` arguments to the equivalent
`where: { field: { equalTo: value } }` form. This matches the
older in-monorepo implementation in
constructive/functions/send-email-link/src/index.ts on the
constructive repo, which has been running against this server
config in production.

This wasn't caught by the existing tests because the GraphQL
clients are mocked with jest.fn().mockResolvedValue(...). The
queries had never been validated against a real schema.

Author: Anmol1696

functions/send-email-link/handler.ts

@@ -6,15 +6,18 @@ 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.
+// Use plural connections with the `where` filter (graphile-connection-filter)
+// rather than `condition:` or singular-by-PK. The constructive server's
+// ConstructivePreset:
+//   1. Extends NoUniqueLookupPreset — disables singular root-field lookups
+//      by unique constraint, including primary key (`database(id:)`,
+//      `user(id:)`).
+//   2. Disables `PgConditionArgumentPlugin` — removes the built-in
+//      `condition:` argument on connections.
+// The supported pattern is `where: { field: { equalTo: var } }`.
 const GetUser = gql`
   query GetUser($userId: UUID!) {
-    users(condition: { id: $userId }, first: 1) {
+    users(where: { id: { equalTo: $userId } }, first: 1) {
       nodes {
         username
         displayName
@@ -26,7 +29,7 @@ const GetUser = gql`
 
 const GetDatabaseInfo = gql`
   query GetDatabaseInfo($databaseId: UUID!) {
-    databases(condition: { id: $databaseId }, first: 1) {
+    databases(where: { id: { equalTo: $databaseId } }, first: 1) {
       nodes {
         sites {
           nodes {
@@ -43,7 +46,7 @@ const GetDatabaseInfo = gql`
                 theme
               }
             }
-            siteModules(condition: { name: "legal_terms_module" }) {
+            siteModules(where: { name: { equalTo: "legal_terms_module" } }) {
               nodes {
                 data
               }