Fix session list cwd pagination

[OldKrab]

Summary

• forward ACP's session/list cwd filter to Codex App Server's thread/list
• apply the filter before App Server pagination and cursor generation
• match Codex CLI ordering with sortKey: "updated_at" and sortDirection: "desc"
• leave limit unset so App Server keeps its default page size
• cover both legacy string-only and newer string-or-array cwd handling
• rely on App Server as the sole owner of CWD filtering
• skip expensive global diagnostics when an empty filtered result is expected

Root cause

CodexAcpClient.listSessions requested a global App Server page, then filtered that page locally by cwd. A requested workspace could therefore receive an empty page with a nextCursor belonging to unrelated global results even when matching sessions existed on later pages.

Passing the scalar ACP cwd through to thread/list is compatible with both App Server forms and makes the returned page and cursor belong to the filtered result set. Local post-pagination filtering is removed because App Server now owns exact CWD filtering.

The request also uses the same updated-at descending ordering as Codex CLI. The CWD, opaque cursor, and ordering parameters are forwarded on every page without specifying a page-size limit.

Empty CWD-filtered listings are valid for new worktrees, so they return immediately. The existing three-query diagnostics remain limited to an empty unfiltered global listing; this avoids turning one filtered request into four App Server scans.

Verification

• npx vitest run src/__tests__/CodexACPAgent/list-sessions.test.ts
• npm run typecheck
• npm test (329 passed, 28 skipped)
• npm run build