feat(workspaces): scaffold feature

Scaffold the workspaces feature package via pnpm turbo gen feature
(single Workspace entity, getWorkspace use case) and hand-wire the
aggregators: bindAll dispatcher (web-next), core-api app router, and
workspace deps. Release-please registration reverted per the root-only
versioning policy (AGENTS.md, ADR-027 retrofit). Pinned @trpc/server
to the repo-wide 11.16.0 resolution so instanceof TRPCError checks
share one module instance.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016j8z4VHjedXDTjEDNg7qHK

packages/core-api/package.json

@@ -17,6 +17,7 @@
     "@repo/core-consent": "workspace:*",
     "@repo/core-dsr": "workspace:*",
     "@repo/core-shared": "workspace:*",
+    "@repo/workspaces": "workspace:*",
     "@trpc/server": "^11.0.0"
   },
   "devDependencies": {