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

apps/web-next/package.json

@@ -19,6 +19,7 @@
     "@repo/core-cms": "workspace:*",
     "@repo/core-shared": "workspace:*",
     "@repo/core-trpc": "workspace:^",
+    "@repo/workspaces": "workspace:*",
     "@sentry/nextjs": "^10.51.0",
     "@tailwindcss/postcss": "^4.3.0",
     "@tanstack/react-query": "^5.96.2",