feat(core-dsr): handlers, dsrRouter, integration tests

Add four protocol-agnostic handlers (export, delete, rectify, restrict)
returning normalized { status, body, headers } responses, and a tRPC
dsrRouter via createDsrRouter(binding) following the factory pattern.

Auth checks: requireAuthenticated middleware gates all four procedures;
cascade-hard delete additionally requires admin role. Integration tests
assert happy-path response shapes, UNAUTHORIZED/FORBIDDEN error codes,
and error passthrough from the DSR service layer.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/core-dsr/package.json

@@ -4,7 +4,8 @@
   "private": true,
   "type": "module",
   "exports": {
-    ".": "./src/index.ts"
+    ".": "./src/index.ts",
+    "./api": "./src/dsr.router.ts"
   },
   "scripts": {
     "build": "tsc --noEmit",
@@ -14,7 +15,9 @@
   },
   "dependencies": {
     "@repo/core-shared": "workspace:*",
-    "payload": "^3.0.0"
+    "@trpc/server": "^11.0.0",
+    "payload": "^3.0.0",
+    "zod": "^3.24.0"
   },
   "devDependencies": {
     "@repo/core-eslint": "workspace:*",