fix: resolve cherry-pick conflicts for COD-24/COD-107 remote host integration

- src/remote-hosts.ts: add missing execAsync = promisify(exec) that was
  implied by intermediate commits not in the cherry-pick set
- src/web/routes/session-routes.ts: add getDataDir import and
  readRemoteCases/readRemoteHosts/toSessionRemote for remote case support
  in quick-start; narrow casePath string|null via resolvedCasePath cast
- test/routes/session-routes.test.ts: add vi.hoisted remoteStore mock for
  remote-hosts.js; fix 'creates session from remote case' test to use
  /api/quick-start (remote cases are not supported on /api/sessions)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/remote-hosts.ts

@@ -13,6 +13,8 @@ import type {
   SessionRemote,
 } from './types.js';
 
+const execAsync = promisify(exec);
+
 const REMOTE_HOSTS_FILE = 'remote-hosts.json';
 const REMOTE_CASES_FILE = 'remote-cases.json';