Fix Relay generating null query text for mutations

Relay v20 treats extend type in server schema as client extensions,
causing all mutation fields to have "text": null in generated artifacts.

Replace the cat-based schema concatenation with a merge script that
collects all extend type Mutation blocks and produces a single
type Mutation definition. The split graphql/ files remain the source
of truth for gqlgen; the merged schema.graphql is generated for Relay.

Signed-off-by: Émile Ré <emile@getprobo.com>

relay.config.json

@@ -7,8 +7,7 @@
   },
   "projects": {
     "core": {
-      "schema": "pkg/server/api/console/v1/graphql/base.graphql",
-      "schemaExtensions": ["pkg/server/api/console/v1/graphql"],
+      "schema": "pkg/server/api/console/v1/schema.graphql",
       "language": "typescript",
       "noFutureProofEnums": true,
       "output": "apps/console/src/__generated__/core",
@@ -23,8 +22,7 @@
       }
     },
     "iam": {
-      "schema": "pkg/server/api/connect/v1/graphql/base.graphql",
-      "schemaExtensions": ["pkg/server/api/connect/v1/graphql"],
+      "schema": "pkg/server/api/connect/v1/schema.graphql",
       "language": "typescript",
       "noFutureProofEnums": true,
       "output": "apps/console/src/__generated__/iam",
@@ -39,8 +37,7 @@
       }
     },
     "trust": {
-      "schema": "pkg/server/api/trust/v1/graphql/base.graphql",
-      "schemaExtensions": ["pkg/server/api/trust/v1/graphql"],
+      "schema": "pkg/server/api/trust/v1/schema.graphql",
       "language": "typescript",
       "noFutureProofEnums": true,
       "customScalarTypes": {