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/validations/permissions.ts

@@ -24,11 +24,6 @@ export const createAreaLeadRoleSchema = z.object({
   color: z.string().max(20).optional().nullable(),
 })
 
-export const updateAreaLeadRoleSchema = z.object({
-  name: z.string().min(1).max(100).optional(),
-  color: z.string().max(20).optional().nullable(),
-})
-
 export const assignAreaLeadSchema = z.object({
   area_lead_role_id: z.string().uuid('Invalid role ID'),
   member_id: z.string().uuid('Invalid member ID'),