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/workspaces/src/di/symbols.ts

@@ -0,0 +1,10 @@
+export const WORKSPACES_SYMBOLS = {
+  IWorkspaceRepository: Symbol.for("workspaces:IWorkspaceRepository"),
+  // Use cases
+  IGetWorkspaceUseCase: Symbol.for("workspaces:IGetWorkspaceUseCase"),
+  // Controllers
+  IGetWorkspaceController: Symbol.for("workspaces:IGetWorkspaceController"),
+  // <gen:event-handler-symbols>
+  // <gen:job-symbols>
+  // <gen:realtime-handler-symbols>
+} as const;