Fix session delete duplication and undo refresh

[Rat0323]

What changed

• ensure session delete actions fire once per click instead of handling both pointerup and click
• refresh the active Codex sidebar after a successful delete undo
• dynamically discover the current app-server-manager-signals-* asset and request function instead of relying on a stale hashed module/export
• retain a full page reload as a fallback when the sidebar refresh signal is unavailable
• add regression coverage for single delete activation and immediate undo refresh

Why

A single delete activation could issue duplicate /delete requests. One request deleted the thread while the second reported Thread not found in local storage, leaving a stale row visible until restart.

After undoing a deletion, the database and rollout file were restored, but an expanded Recent section did not update until it was collapsed and expanded again. The refresh helper referenced an old hashed Codex asset and export name, so the current desktop build never received the sidebar refresh signal.

User impact

• deleting a session no longer produces a misleading failure after a successful deletion
• undoing a session deletion makes the restored session appear immediately while Recent remains expanded

Validation

• cargo test -p codex-plus-core --test cdp_bridge — 97 passed
• npm test --prefix apps/codex-plus-manager — 36 passed
• cargo fmt --check
• git diff --check

npm run check --prefix apps/codex-plus-manager is currently blocked by the repository tsconfig using the removed TypeScript baseUrl option (TS5102), unrelated to this JavaScript/Rust-test-only change.