coder(providers): remove retired cursor and copilot providers

Drop both retired providers from BooCoder's provider layer: acp-spawn argv cases, provider-manifest mode blocks + manifest keys, provider-commands maps, the provider-snapshot cursor model-CLI branch (+ orphaned exec/promisify imports), the agent-probe copilot ACP-detect branch, and the now-dead cursor-models module + its test. The PROVIDERS registry array already lacked both. Built-ins unchanged: claude, opencode, goose, qwen, native boocode.

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

apps/coder/src/services/acp-spawn.ts

@@ -6,10 +6,6 @@ export function resolveAcpSpawnArgs(agent: string): string[] | null {
     case 'opencode':
     case 'goose':
       return ['acp'];
-    case 'cursor':
-      return ['acp'];
-    case 'copilot':
-      return ['--acp'];
     case 'qwen':
       return ['--acp'];
     default:
@@ -18,12 +14,5 @@ export function resolveAcpSpawnArgs(agent: string): string[] | null {
 }
 
 export function resolveAcpProbeBinaries(agent: string): string[] {
-  switch (agent) {
-    case 'cursor':
-      return ['cursor-agent', 'agent'];
-    case 'copilot':
-      return ['copilot'];
-    default:
-      return [agent];
-  }
+  return [agent];
 }