refactor: dead-code cleanup + drop the lib/types shim (slice 9)

- Delete orphaned components (theme-provider, task-claim-button), the unused
  roleDisplayName helper, the fully-dead cleanupRateLimits, the 6 never-imported
  validation schemas (signIn/signUp/createSpace/joinSpace — a replaced auth flow;
  proposalStatuses; updateAreaLeadRoleSchema).
- Migrate all @/lib/types importers to the canonical @/types/domain and delete
  the compatibility shim.

tsc 0, 635 tests green, lint clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/role-labels.ts

@@ -47,8 +47,3 @@ export async function getRoleLabelMap(
   return map
 }
 
-export function roleDisplayName(map: Record<string, RoleLabel> | null | undefined, role: string): string {
-  if (map && map[role]) return map[role].name
-  const d = DEFAULT_ROLE_LABELS[role as BuiltinRole]
-  return d ? d.name : role
-}