feat(shared-ts): federation shared utilities for apollo subgraphs

- RouterAuthGuard: validate Router-Authorization header (ADR-036)

- DataLoader factory: request-scoped batching (ADR-035)

- ScopeTokenService: Redis-backed scope token (ADR-041)

- GraphqlContext: build context from HTTP headers

- FederationExceptionFilter: HTTP-to-GraphQL error mapping

packages/shared-ts/package.json

@@ -11,6 +11,10 @@
     "./bff": {
       "types": "./dist/bff/index.d.ts",
       "default": "./dist/bff/index.js"
+    },
+    "./federation": {
+      "types": "./dist/federation/index.d.ts",
+      "default": "./dist/federation/index.js"
     }
   },
   "scripts": {
@@ -24,8 +28,11 @@
     "@nestjs/common": "^10.4.0",
     "@nestjs/core": "^10.4.0",
     "@paralleldrive/cuid2": "^2.2.2",
+    "dataloader": "^2.2.2",
     "drizzle-orm": "^0.31.0",
+    "graphql": "^16.9.0",
     "graphql-yoga": "^5.7.0",
+    "ioredis": "^5.4.0",
     "kafkajs": "^2.2.4",
     "pino": "^9.4.0",
     "prom-client": "^15.1.0",