Code tab: add bulk-delete for sessions, and don't persist sessions that never submitted a prompt

Summary

Two related gaps in how the desktop app's Code tab manages server-side session records.

1. No way to bulk-delete Code-tab sessions

There is currently no "select multiple" / "clear all" path for Code-tab sessions. When unwanted or empty records build up, removing them one at a time is impractical — and because the records are server-side, clearing local app data and relaunching has no effect.

Request: a bulk-delete / multi-select / "clear all" option, ideally including a server-side purge so the account's session list can actually be cleaned up.

2. Sessions that never submitted a prompt are persisted as Code-tab records

An interactive session that is opened but never submits a prompt — e.g. one that only opens and dismisses a UI dialog — can still create a server-side session record that appears in the Code tab. These have no real prompt or transcript (the body is just a UI-event placeholder). Short-lived or automated invocations of the CLI can therefore leave empty records behind.

Expected: a session that submits no prompt and performs no task should not create a durable, listed Code-tab record.

Environment

• Claude desktop app — Code tab
• macOS, Apple Silicon