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) <[email protected]>

components/task-claim-button.tsx

@@ -1,64 +0,0 @@
-'use client'
-
-import { useState } from 'react'
-import { claimTask, completeTask } from '@/lib/actions'
-
-export function ClaimButton({ taskId }: { taskId: string }) {
-  const [loading, setLoading] = useState(false)
-  const [done, setDone] = useState(false)
-
-  async function handleClaim() {
-    setLoading(true)
-    const result = await claimTask(taskId)
-    if (!result.error) setDone(true)
-    setLoading(false)
-  }
-
-  if (done) {
-    return (
-      <span className="font-mono text-[10px] text-primary bg-primary/10 px-2 py-0.5 rounded">
-        CLAIMED
-      </span>
-    )
-  }
-
-  return (
-    <button
-      onClick={handleClaim}
-      disabled={loading}
-      className="font-mono text-[10px] border border-border px-2 py-0.5 rounded hover:border-primary hover:text-primary transition disabled:opacity-50"
-    >
-      {loading ? '...' : 'CLAIM'}
-    </button>
-  )
-}
-
-export function CompleteButton({ taskId }: { taskId: string }) {
-  const [loading, setLoading] = useState(false)
-  const [done, setDone] = useState(false)
-
-  async function handleComplete() {
-    setLoading(true)
-    const result = await completeTask(taskId)
-    if (!result.error) setDone(true)
-    setLoading(false)
-  }
-
-  if (done) {
-    return (
-      <span className="font-mono text-[10px] text-muted-foreground bg-muted px-2 py-0.5 rounded">
-        DONE
-      </span>
-    )
-  }
-
-  return (
-    <button
-      onClick={handleComplete}
-      disabled={loading}
-      className="font-mono text-[10px] border border-green-200 text-green-700 px-2 py-0.5 rounded hover:bg-green-50 transition disabled:opacity-50"
-    >
-      {loading ? '...' : 'DONE'}
-    </button>
-  )
-}

components/theme-provider.tsx

@@ -1,11 +0,0 @@
-'use client'
-
-import * as React from 'react'
-import {
-  ThemeProvider as NextThemesProvider,
-  type ThemeProviderProps,
-} from 'next-themes'
-
-export function ThemeProvider({ children, ...props }: ThemeProviderProps) {
-  return <NextThemesProvider {...props}>{children}</NextThemesProvider>
-}